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The wakeup in preemptive (wip) monitor verifies if the
wakeup events always take place with preemption disabled:
|
|
v
#==================#
H preemptive H <+
#==================# |
| |
| preempt_disable | preempt_enable
v |
sched_waking +------------------+ |
+--------------- | | |
| | non_preemptive | |
+--------------> | | -+
+------------------+
The wakeup event always takes place with preemption disabled because
of the scheduler synchronization. However, because the preempt_count
and its trace event are not atomic with regard to interrupts, some
inconsistencies might happen.
The documentation illustrates one of these cases.
Link: https://lkml.kernel.org/r/c98ca678df81115fddc04921b3c79720c836b18f.1659052063.git.bristot@kernel.org
Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Gabriele Paoloni <gpaoloni@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Tao Zhou <tao.zhou@linux.dev>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
THIS CODE IS NOT LINKED TO THE MAKEFILE.
This model does not compile because it lacks the instrumentation
part, which will be added next. In the typical case, there will be
only one patch, but it was split into two patches for educational
purposes.
This is the direct output this command line:
$ dot2k -d tools/verification/models/wip.dot -t per_cpu
Link: https://lkml.kernel.org/r/5eb7a9118917e8a814c5e49853a72fc62be0a101.1659052063.git.bristot@kernel.org
Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Gabriele Paoloni <gpaoloni@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Tao Zhou <tao.zhou@linux.dev>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
dot2c is a tool that transforms an automata in the graphiviz .dot file
into an C representation of the automata.
usage: dot2c [-h] dot_file
dot2c: converts a .dot file into a C structure
positional arguments:
dot_file The dot file to be converted
optional arguments:
-h, --help show this help message and exit
Link: https://lkml.kernel.org/r/b26204ba9509c80bcda31b76cdea31ddb188cd24.1659052063.git.bristot@kernel.org
Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Gabriele Paoloni <gpaoloni@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Tao Zhou <tao.zhou@linux.dev>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Add the runtime-verification.rst document, explaining the basics of RV
and how to use the interface.
Link: https://lkml.kernel.org/r/4be7d1a88ab1e2eb0767521e1ab52a149a154bc4.1659052063.git.bristot@kernel.org
Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Gabriele Paoloni <gpaoloni@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Tao Zhou <tao.zhou@linux.dev>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
In Linux terms, the runtime verification monitors are encapsulated
inside the "RV monitor" abstraction. The "RV monitor" includes a set
of instances of the monitor (per-cpu monitor, per-task monitor, and
so on), the helper functions that glue the monitor to the system
reference model, and the trace output as a reaction for event parsing
and exceptions, as depicted below:
Linux +----- RV Monitor ----------------------------------+ Formal
Realm | | Realm
+-------------------+ +----------------+ +-----------------+
| Linux kernel | | Monitor | | Reference |
| Tracing | -> | Instance(s) | <- | Model |
| (instrumentation) | | (verification) | | (specification) |
+-------------------+ +----------------+ +-----------------+
| | |
| V |
| +----------+ |
| | Reaction | |
| +--+--+--+-+ |
| | | | |
| | | +-> trace output ? |
+------------------------|--|----------------------+
| +----> panic ?
+-------> <user-specified>
Add the rv/da_monitor.h, enabling automatic code generation for the
*Monitor Instance(s)* using C macros, and code to support it.
The benefits of the usage of macro for monitor synthesis are 3-fold as it:
- Reduces the code duplication;
- Facilitates the bug fix/improvement;
- Avoids the case of developers changing the core of the monitor code
to manipulate the model in a (let's say) non-standard way.
This initial implementation presents three different types of monitor
instances:
- DECLARE_DA_MON_GLOBAL(name, type)
- DECLARE_DA_MON_PER_CPU(name, type)
- DECLARE_DA_MON_PER_TASK(name, type)
The first declares the functions for a global deterministic automata monitor,
the second for monitors with per-cpu instances, and the third with per-task
instances.
Link: https://lkml.kernel.org/r/51b0bf425a281e226dfeba7401d2115d6091f84e.1659052063.git.bristot@kernel.org
Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Gabriele Paoloni <gpaoloni@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Tao Zhou <tao.zhou@linux.dev>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Formally, a deterministic automaton, denoted by G, is defined as a
quintuple:
G = { X, E, f, x_0, X_m }
where:
- X is the set of states;
- E is the finite set of events;
- x_0 is the initial state;
- X_m (subset of X) is the set of marked states.
- f : X x E -> X $ is the transition function. It defines the
state transition in the occurrence of a event from E in
the state X. In the special case of deterministic automata,
the occurrence of the event in E in a state in X has a
deterministic next state from X.
An automaton can also be represented using a graphical format of
vertices (nodes) and edges. The open-source tool Graphviz can produce
this graphic format using the (textual) DOT language as the source code.
The dot2c tool presented in this paper:
De Oliveira, Daniel Bristot; Cucinotta, Tommaso; De Oliveira, Romulo
Silva. Efficient formal verification for the Linux kernel. In:
International Conference on Software Engineering and Formal Methods.
Springer, Cham, 2019. p. 315-332.
Translates a deterministic automaton in the DOT format into a C
source code representation that to be used for monitoring.
This header file implements helper functions to facilitate the usage
of the C output from dot2c/k for monitoring.
Link: https://lkml.kernel.org/r/563234f2bfa84b540f60cf9e39c2d9f0eea95a55.1659052063.git.bristot@kernel.org
Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Gabriele Paoloni <gpaoloni@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Tao Zhou <tao.zhou@linux.dev>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
A runtime monitor can cause a reaction to the detection of an
exception on the model's execution. By default, the monitors have
tracing reactions, printing the monitor output via tracepoints.
But other reactions can be added (on-demand) via this interface.
The user interface resembles the kernel tracing interface and
presents these files:
"available_reactors"
- Reading shows the available reactors, one per line.
For example:
# cat available_reactors
nop
panic
printk
"reacting_on"
- It is an on/off general switch for reactors, disabling
all reactions.
"monitors/MONITOR/reactors"
- List available reactors, with the select reaction for the given
MONITOR inside []. The default one is the nop (no operation)
reactor.
- Writing the name of a reactor enables it to the given
MONITOR.
For example:
# cat monitors/wip/reactors
[nop]
panic
printk
# echo panic > monitors/wip/reactors
# cat monitors/wip/reactors
nop
[panic]
printk
Link: https://lkml.kernel.org/r/1794eb994637457bdeaa6bad0b8263d2f7eece0c.1659052063.git.bristot@kernel.org
Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Gabriele Paoloni <gpaoloni@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Tao Zhou <tao.zhou@linux.dev>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
RV is a lightweight (yet rigorous) method that complements classical
exhaustive verification techniques (such as model checking and
theorem proving) with a more practical approach to complex systems.
RV works by analyzing the trace of the system's actual execution,
comparing it against a formal specification of the system behavior.
RV can give precise information on the runtime behavior of the
monitored system while enabling the reaction for unexpected
events, avoiding, for example, the propagation of a failure on
safety-critical systems.
The development of this interface roots in the development of the
paper:
De Oliveira, Daniel Bristot; Cucinotta, Tommaso; De Oliveira, Romulo
Silva. Efficient formal verification for the Linux kernel. In:
International Conference on Software Engineering and Formal Methods.
Springer, Cham, 2019. p. 315-332.
And:
De Oliveira, Daniel Bristot. Automata-based formal analysis
and verification of the real-time Linux kernel. PhD Thesis, 2020.
The RV interface resembles the tracing/ interface on purpose. The current
path for the RV interface is /sys/kernel/tracing/rv/.
It presents these files:
"available_monitors"
- List the available monitors, one per line.
For example:
# cat available_monitors
wip
wwnr
"enabled_monitors"
- Lists the enabled monitors, one per line;
- Writing to it enables a given monitor;
- Writing a monitor name with a '!' prefix disables it;
- Truncating the file disables all enabled monitors.
For example:
# cat enabled_monitors
# echo wip > enabled_monitors
# echo wwnr >> enabled_monitors
# cat enabled_monitors
wip
wwnr
# echo '!wip' >> enabled_monitors
# cat enabled_monitors
wwnr
# echo > enabled_monitors
# cat enabled_monitors
#
Note that more than one monitor can be enabled concurrently.
"monitoring_on"
- It is an on/off general switcher for monitoring. Note
that it does not disable enabled monitors or detach events,
but stop the per-entity monitors of monitoring the events
received from the system. It resembles the "tracing_on" switcher.
"monitors/"
Each monitor will have its one directory inside "monitors/". There
the monitor specific files will be presented.
The "monitors/" directory resembles the "events" directory on
tracefs.
For example:
# cd monitors/wip/
# ls
desc enable
# cat desc
wakeup in preemptive per-cpu testing monitor.
# cat enable
0
For further information, see the comments in the header of
kernel/trace/rv/rv.c from this patch.
Link: https://lkml.kernel.org/r/a4bfe038f50cb047bfb343ad0e12b0e646ab308b.1659052063.git.bristot@kernel.org
Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Gabriele Paoloni <gpaoloni@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Tao Zhou <tao.zhou@linux.dev>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
When a ftrace_bug happens (where ftrace fails to modify a location) it is
helpful to have what was at that location as well as what was expected to
be there.
But with the conversion to text_poke() the variable that assigns the
expected for debugging was dropped. Unfortunately, I noticed this when I
needed it. Add it back.
Link: https://lkml.kernel.org/r/20220726101851.069d2e70@gandalf.local.home
Cc: "x86@kernel.org" <x86@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@vger.kernel.org
Fixes: 768ae4406a5c ("x86/ftrace: Use text_poke()")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
If an instance of tracing enables the same trace event as another
instance, or the top level instance, or even perf, then the va_list passed
into some tracepoints can be used more than once.
As va_list can only be traversed once, this can cause issues:
# cat /sys/kernel/tracing/instances/qla2xxx/trace
cat-56106 [012] ..... 2419873.470098: ql_dbg_log: qla2xxx [0000:05:00.0]-1054:14: Entered (null).
cat-56106 [012] ..... 2419873.470101: ql_dbg_log: qla2xxx [0000:05:00.0]-1000:14: Entered ×+<96>²Ü<98>^H.
cat-56106 [012] ..... 2419873.470102: ql_dbg_log: qla2xxx [0000:05:00.0]-1006:14: Prepare to issue mbox cmd=0xde589000.
# cat /sys/kernel/tracing/trace
cat-56106 [012] ..... 2419873.470097: ql_dbg_log: qla2xxx [0000:05:00.0]-1054:14: Entered qla2x00_get_firmware_state.
cat-56106 [012] ..... 2419873.470100: ql_dbg_log: qla2xxx [0000:05:00.0]-1000:14: Entered qla2x00_mailbox_command.
cat-56106 [012] ..... 2419873.470102: ql_dbg_log: qla2xxx [0000:05:00.0]-1006:14: Prepare to issue mbox cmd=0x69.
The instance version is corrupted because the top level instance iterated
the va_list first.
Use va_copy() in the __assign_vstr() macro to make sure that each trace
event for each use case gets a fresh va_list.
Link: https://lore.kernel.org/all/259d53a5-958e-6508-4e45-74dba2821242@marvell.com/
Link: https://lkml.kernel.org/r/20220719182004.21daa83e@gandalf.local.home
Fixes: 0563231f93c6d ("tracing/events: Add __vstring() and __assign_vstr() helper macros")
Reported-by: Arun Easi <aeasi@marvell.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Instead of open coding a __dynamic_array() with a fixed length (which
defeats the purpose of the dynamic array in the first place). Use the new
__vstring() helper that will use a va_list and only write enough of the
string into the ring buffer that is needed.
Link: https://lkml.kernel.org/r/20220724191650.236b1355@rorschach.local.home
Cc: Marek Lindner <mareklindner@neomailbox.ch>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Simon Wunderlich <sw@simonwunderlich.de>
Cc: Antonio Quartulli <a@unstable.cc>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: b.a.t.m.a.n@lists.open-mesh.org
Cc: netdev@vger.kernel.org
Acked-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Instead of open coding a __dynamic_array() with a fixed length (which
defeats the purpose of the dynamic array in the first place). Use the new
__vstring() helper that will use a va_list and only write enough of the
string into the ring buffer that is needed.
Link: https://lkml.kernel.org/r/20220719112719.17e796c6@gandalf.local.home
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-usb@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mediatek@lists.infradead.org
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Tested-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
The commit 208003254c32 ("selftests/kprobe: Do not test for GRP/
without event failures") removed a syntax which is no more cause
a syntax error (NO_EVENT_NAME error with GRP/).
However, there are another case (NO_EVENT_NAME error without GRP/)
which causes a same error. This adds a test for that case.
Link: https://lkml.kernel.org/r/165812790993.1377963.9762767354560397298.stgit@devnote2
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
A new feature is added where kprobes (and other probes) do not need to
explicitly state the event name when creating a probe. The event name will
come from what is being attached.
That is:
# echo 'p:foo/ vfs_read' > kprobe_events
Will no longer error, but instead create an event:
# cat kprobe_events
p:foo/p_vfs_read_0 vfs_read
This should not be tested as an error case anymore. Remove it from the
selftest as now this feature "breaks" the selftest as it no longer fails
as expected.
Link: https://lore.kernel.org/all/1656296348-16111-1-git-send-email-quic_linyyuan@quicinc.com/
Link: https://lkml.kernel.org/r/20220712161707.6dc08a14@gandalf.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Add kprobe and eprobe event test for new GRP/ only format.
Link: https://lore.kernel.org/all/1656296348-16111-5-git-send-email-quic_linyyuan@quicinc.com/
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Linyu Yuan <quic_linyyuan@quicinc.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Currently when creating a specific group of trace events,
take kprobe event as example, the user must use the following format:
p:GRP/EVENT [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS],
which means user must enter EVENT name, one example is:
echo 'p:usb_gadget/config_usb_cfg_link config_usb_cfg_link $arg1' >> kprobe_events
It is not simple if there are too many entries because the event name is
the same as symbol name.
This change allows user to specify no EVENT name, format changed as:
p:GRP/ [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS]
It will generate event name automatically and one example is:
echo 'p:usb_gadget/ config_usb_cfg_link $arg1' >> kprobe_events.
Link: https://lore.kernel.org/all/1656296348-16111-4-git-send-email-quic_linyyuan@quicinc.com/
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Linyu Yuan <quic_linyyuan@quicinc.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
traceprobe_parse_event_name() already validate SYSTEM and EVENT name,
there is no need to call is_good_name() after it.
Link: https://lore.kernel.org/all/1656296348-16111-3-git-send-email-quic_linyyuan@quicinc.com/
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Linyu Yuan <quic_linyyuan@quicinc.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Instead of open coding a __dynamic_array() with a fixed length (which
defeats the purpose of the dynamic array in the first place). Use the new
__vstring() helper that will use a va_list and only write enough of the
string into the ring buffer that is needed.
Link: https://lkml.kernel.org/r/20220705224751.271015450@goodmis.org
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Instead of open coding a __dynamic_array() with a fixed length (which
defeats the purpose of the dynamic array in the first place). Use the new
__vstring() helper that will use a va_list and only write enough of the
string into the ring buffer that is needed.
Link: https://lkml.kernel.org/r/20220705224750.896553364@goodmis.org
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Instead of open coding a __dynamic_array() with a fixed length (which
defeats the purpose of the dynamic array in the first place). Use the new
__vstring() helper that will use a va_list and only write enough of the
string into the ring buffer that is needed.
Link: https://lkml.kernel.org/r/20220705224750.715763972@goodmis.org
Cc: Fred Herard <fred.herard@oracle.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Instead of open coding a __dynamic_array() with a fixed length (which
defeats the purpose of the dynamic array in the first place). Use the new
__vstring() helper that will use a va_list and only write enough of the
string into the ring buffer that is needed.
Link: https://lkml.kernel.org/r/20220705224750.532345354@goodmis.org
Cc: Bin Liu <b-liu@ti.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Instead of open coding a __dynamic_array() with a fixed length (which
defeats the purpose of the dynamic array in the first place). Use the new
__vstring() helper that will use a va_list and only write enough of the
string into the ring buffer that is needed.
Link: https://lkml.kernel.org/r/20220705224750.172301548@goodmis.org
Cc: Mathias Nyman <mathias.nyman@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Instead of open coding a __dynamic_array() with a fixed length (which
defeats the purpose of the dynamic array in the first place). Use the new
__vstring() helper that will use a va_list and only write enough of the
string into the ring buffer that is needed.
Link: https://lkml.kernel.org/r/20220705224749.991587733@goodmis.org
Cc: Peter Chen <peter.chen@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Instead of open coding a __dynamic_array() with a fixed length (which
defeats the purpose of the dynamic array in the first place). Use the new
__vstring() helper that will use a va_list and only write enough of the
string into the ring buffer that is needed.
Link: https://lkml.kernel.org/r/20220705224749.806599472@goodmis.org
Cc: Gregory Greenman <gregory.greenman@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Kalle Valo <kvalo@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Acked-by: Kalle Valo <kvalo@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Instead of open coding a __dynamic_array() with a fixed length (which
defeats the purpose of the dynamic array in the first place). Use the new
__vstring() helper that will use a va_list and only write enough of the
string into the ring buffer that is needed.
Link: https://lkml.kernel.org/r/20220705224749.622796175@goodmis.org
Cc: Arend van Spriel <aspriel@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Franky Lin <franky.lin@broadcom.com>
Cc: Hante Meuleman <hante.meuleman@broadcom.com>
Cc: Kalle Valo <kvalo@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: linux-wireless@vger.kernel.org
Cc: brcm80211-dev-list.pdl@broadcom.com
Cc: SHA-cyfmac-dev-list@infineon.com
Cc: netdev@vger.kernel.org
Acked-by: Kalle Valo <kvalo@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Instead of open coding a __dynamic_array() with a fixed length (which
defeats the purpose of the dynamic array in the first place). Use the new
__vstring() helper that will use a va_list and only write enough of the
string into the ring buffer that is needed.
Link: https://lkml.kernel.org/r/20220705224749.430339634@goodmis.org
Cc: Kalle Valo <kvalo@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: ath10k@lists.infradead.org
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: ath11k@lists.infradead.org
Acked-by: Kalle Valo <kvalo@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Instead of open coding a __dynamic_array() with a fixed length (which
defeats the purpose of the dynamic array in the first place). Use the new
__vstring() helper that will use a va_list and only write enough of the
string into the ring buffer that is needed.
Link: https://lkml.kernel.org/r/20220705224749.239494531@goodmis.org
Cc: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: linux-rdma@vger.kernel.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
There's several places that open code the following logic:
TP_STRUCT__entry(__dynamic_array(char, msg, MSG_MAX)),
TP_fast_assign(vsnprintf(__get_str(msg), MSG_MAX, vaf->fmt, *vaf->va);)
To load a string created by variable array va_list.
The main issue with this approach is that "MSG_MAX" usage in the
__dynamic_array() portion. That actually just reserves the MSG_MAX in the
event, and even wastes space because there's dynamic meta data also saved
in the event to denote the offset and size of the dynamic array. It would
have been better to just use a static __array() field.
Instead, create __vstring() and __assign_vstr() that work like __string
and __assign_str() but instead of taking a destination string to copy,
take a format string and a va_list pointer and fill in the values.
It uses the helper:
#define __trace_event_vstr_len(fmt, va) \
({ \
va_list __ap; \
int __ret; \
\
va_copy(__ap, *(va)); \
__ret = vsnprintf(NULL, 0, fmt, __ap) + 1; \
va_end(__ap); \
\
min(__ret, TRACE_EVENT_STR_MAX); \
})
To figure out the length to store the string. It may be slightly slower as
it needs to run the vsnprintf() twice, but it now saves space on the ring
buffer.
Link: https://lkml.kernel.org/r/20220705224749.053570613@goodmis.org
Cc: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Kalle Valo <kvalo@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Arend van Spriel <aspriel@gmail.com>
Cc: Franky Lin <franky.lin@broadcom.com>
Cc: Hante Meuleman <hante.meuleman@broadcom.com>
Cc: Gregory Greenman <gregory.greenman@intel.com>
Cc: Peter Chen <peter.chen@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mathias Nyman <mathias.nyman@intel.com>
Cc: Chunfeng Yun <chunfeng.yun@mediatek.com>
Cc: Bin Liu <b-liu@ti.com>
Cc: Marek Lindner <mareklindner@neomailbox.ch>
Cc: Simon Wunderlich <sw@simonwunderlich.de>
Cc: Antonio Quartulli <a@unstable.cc>
Cc: Sven Eckelmann <sven@narfation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Jim Cromie <jim.cromie@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
The dev field of the neigh_create event uses __dynamic_array() with a
fixed size, which defeats the purpose of __dynamic_array(). Looking at the
logic, as it already uses __assign_str(), just use the same logic in
__string to create the size needed. It appears that because "dev" can be
NULL, it needs the check. But __string() can have the same checks as
__assign_str() so use them there too.
Link: https://lkml.kernel.org/r/20220705183741.35387e3f@rorschach.local.home
Cc: David Ahern <dsahern@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Acked-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
The fib_lookup_table and fib6_lookup_table events declare name as a
dynamic_array, but also give it a fixed size, which defeats the purpose of
the dynamic array, especially since the dynamic array also includes meta
data in the event to specify its size.
Since the size of the name is at most 16 bytes (defined by IFNAMSIZ),
it is not worth spending the effort to determine the size of the string.
Just use a fixed size array and copy into it. This will save 4 bytes that
are used for the meta data that saves the size and position of a dynamic
array, and even slightly speed up the event processing.
Link: https://lkml.kernel.org/r/20220704091436.3705edbf@rorschach.local.home
Cc: David S. Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Acked-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
The trace event devlink_trap_report uses the __dynamic_array() macro to
determine the size of the input_dev_name field. This is because it needs
to test the dev field for NULL, and will use "NULL" if it is. But it also
has the size of the dynamic array as a fixed IFNAMSIZ bytes. This defeats
the purpose of the dynamic array, as this will reserve that amount of
bytes on the ring buffer, and to make matters worse, it will even save
that size in the event as the event expects it to be dynamic (for which it
is not).
Since IFNAMSIZ is just 16 bytes, just make it a static array and this will
remove the meta data from the event that records the size.
Link: https://lkml.kernel.org/r/20220712185820.002d9fb5@gandalf.local.home
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Jiri Pirko <jiri@nvidia.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: netdev@vger.kernel.org
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Tested-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
When I look into implements of create_hist_fields(), I think there can be
following two simplifications:
1. If something wrong happened in parse_var_defs(), free_var_defs() would
have been called in it, so no need goto free again after calling it;
2. After calling create_key_fields(), regardless of the value of 'ret', it
then always runs into 'out: ', so the judge of 'ret' is redundant.
Link: https://lkml.kernel.org/r/20220630013152.164871-1-zhengyejian1@huawei.com
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Reviewed-by: Tom Rix <trix@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
It is better and enough to use KSYM_NAME_LEN for kprobes
in samples, no need to define and use the other values.
Link: https://lkml.kernel.org/r/1654651402-21552-1-git-send-email-yangtiezhu@loongson.cn
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This symbol is not used outside of fprobe_example.c, so marks it static.
Fixes the following warning:
sparse warnings: (new ones prefixed by >>)
>> samples/fprobe/fprobe_example.c:23:15: sparse: sparse: symbol 'sample_probe'
was not declared. Should it be static?
Link: https://lkml.kernel.org/r/20220606075659.674556-1-sunliming@kylinos.cn
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: sunliming <sunliming@kylinos.cn>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
It was brought up that on ARMv7, that because the FUNCTION_TRACER does not
use nops to keep function tracing disabled because of the use of a link
register, it does have some performance impact.
The start of functions when -pg is used to compile the kernel is:
push {lr}
bl 8010e7c0 <__gnu_mcount_nc>
When function tracing is tuned off, it becomes:
push {lr}
add sp, sp, #4
Which just puts the stack back to its normal location. But these two
instructions at the start of every function does incur some overhead.
Be more honest in the Kconfig FUNCTION_TRACER description and specify that
the overhead being in the noise was x86 specific, but other architectures
may vary.
Link: https://lore.kernel.org/all/20220705105416.GE5208@pengutronix.de/
Link: https://lkml.kernel.org/r/20220706161231.085a83da@gandalf.local.home
Reported-by: Sascha Hauer <sha@pengutronix.de>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
If you drop into kdb and type "ftdump" you'll get a sleeping while
atomic warning from memory allocation in trace_find_next_entry().
This appears to have been caused by commit ff895103a84a ("tracing:
Save off entry when peeking at next entry"), which added the
allocation in that path. The problematic commit was already fixed by
commit 8e99cf91b99b ("tracing: Do not allocate buffer in
trace_find_next_entry() in atomic") but that fix missed the kdb case.
The fix here is easy: just move the assignment of the static buffer to
the place where it should have been to begin with:
trace_init_global_iter(). That function is called in two places, once
is right before the assignment of the static buffer added by the
previous fix and once is in kdb.
Note that it appears that there's a second static buffer that we need
to assign that was added in commit efbbdaa22bb7 ("tracing: Show real
address for trace event arguments"), so we'll move that too.
Link: https://lkml.kernel.org/r/20220708170919.1.I75844e5038d9425add2ad853a608cb44bb39df40@changeid
Fixes: ff895103a84a ("tracing: Save off entry when peeking at next entry")
Fixes: efbbdaa22bb7 ("tracing: Show real address for trace event arguments")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This reverts commit 46bbe5c671e06f070428b9be142cc4ee5cedebac.
As commit 46bbe5c671e0 ("tracing: fix double free") said, the
"double free" problem reported by clang static analyzer is:
> In parse_var_defs() if there is a problem allocating
> var_defs.expr, the earlier var_defs.name is freed.
> This free is duplicated by free_var_defs() which frees
> the rest of the list.
However, if there is a problem allocating N-th var_defs.expr:
+ in parse_var_defs(), the freed 'earlier var_defs.name' is
actually the N-th var_defs.name;
+ then in free_var_defs(), the names from 0th to (N-1)-th are freed;
IF ALLOCATING PROBLEM HAPPENED HERE!!! -+
\
|
0th 1th (N-1)-th N-th V
+-------------+-------------+-----+-------------+-----------
var_defs: | name | expr | name | expr | ... | name | expr | name | ///
+-------------+-------------+-----+-------------+-----------
These two frees don't act on same name, so there was no "double free"
problem before. Conversely, after that commit, we get a "memory leak"
problem because the above "N-th var_defs.name" is not freed.
If enable CONFIG_DEBUG_KMEMLEAK and inject a fault at where the N-th
var_defs.expr allocated, then execute on shell like:
$ echo 'hist:key=call_site:val=$v1,$v2:v1=bytes_req,v2=bytes_alloc' > \
/sys/kernel/debug/tracing/events/kmem/kmalloc/trigger
Then kmemleak reports:
unreferenced object 0xffff8fb100ef3518 (size 8):
comm "bash", pid 196, jiffies 4295681690 (age 28.538s)
hex dump (first 8 bytes):
76 31 00 00 b1 8f ff ff v1......
backtrace:
[<0000000038fe4895>] kstrdup+0x2d/0x60
[<00000000c99c049a>] event_hist_trigger_parse+0x206f/0x20e0
[<00000000ae70d2cc>] trigger_process_regex+0xc0/0x110
[<0000000066737a4c>] event_trigger_write+0x75/0xd0
[<000000007341e40c>] vfs_write+0xbb/0x2a0
[<0000000087fde4c2>] ksys_write+0x59/0xd0
[<00000000581e9cdf>] do_syscall_64+0x3a/0x80
[<00000000cf3b065c>] entry_SYSCALL_64_after_hwframe+0x46/0xb0
Link: https://lkml.kernel.org/r/20220711014731.69520-1-zhengyejian1@huawei.com
Cc: stable@vger.kernel.org
Fixes: 46bbe5c671e0 ("tracing: fix double free")
Reported-by: Hulk Robot <hulkci@huawei.com>
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Looking at the conditional lock acquire functions in the kernel due to
the new sparse support (see commit 4a557a5d1a61 "sparse: introduce
conditional lock acquire function attribute"), it became obvious that
the lockref code has a couple of them, but they don't match the usual
naming convention for the other ones, and their return value logic is
also reversed.
In the other very similar places, the naming pattern is '*_and_lock()'
(eg 'atomic_put_and_lock()' and 'refcount_dec_and_lock()'), and the
function returns true when the lock is taken.
The lockref code is superficially very similar to the refcount code,
only with the special "atomic wrt the embedded lock" semantics. But
instead of the '*_and_lock()' naming it uses '*_or_lock()'.
And instead of returning true in case it took the lock, it returns true
if it *didn't* take the lock.
Now, arguably the reflock code is quite logical: it really is a "either
decrement _or_ lock" kind of situation - and the return value is about
whether the operation succeeded without any special care needed.
So despite the similarities, the differences do make some sense, and
maybe it's not worth trying to unify the different conditional locking
primitives in this area.
But while looking at this all, it did become obvious that the
'lockref_get_or_lock()' function hasn't actually had any users for
almost a decade.
The only user it ever had was the shortlived 'd_rcu_to_refcount()'
function, and it got removed and replaced with 'lockref_get_not_dead()'
back in 2013 in commits 0d98439ea3c6 ("vfs: use lockred 'dead' flag to
mark unrecoverably dead dentries") and e5c832d55588 ("vfs: fix dentry
RCU to refcounting possibly sleeping dput()")
In fact, that single use was removed less than a week after the whole
function was introduced in commit b3abd80250c1 ("lockref: add
'lockref_get_or_lock() helper") so this function has been around for a
decade, but only had a user for six days.
Let's just put this mis-designed and unused function out of its misery.
We can think about the naming and semantic oddities of the remaining
'lockref_put_or_lock()' later, but at least that function has users.
And while the naming is different and the return value doesn't match,
that function matches the whole '{atomic,refcount}_dec_and_test()'
pattern much better (ie the magic happens when the count goes down to
zero, not when it is incremented from zero).
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The kernel tends to try to avoid conditional locking semantics because
it makes it harder to think about and statically check locking rules,
but we do have a few fundamental locking primitives that take locks
conditionally - most obviously the 'trylock' functions.
That has always been a problem for 'sparse' checking for locking
imbalance, and we've had a special '__cond_lock()' macro that we've used
to let sparse know how the locking works:
# define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0)
so that you can then use this to tell sparse that (for example) the
spinlock trylock macro ends up acquiring the lock when it succeeds, but
not when it fails:
#define raw_spin_trylock(lock) __cond_lock(lock, _raw_spin_trylock(lock))
and then sparse can follow along the locking rules when you have code like
if (!spin_trylock(&dentry->d_lock))
return LRU_SKIP;
.. sparse sees that the lock is held here..
spin_unlock(&dentry->d_lock);
and sparse ends up happy about the lock contexts.
However, this '__cond_lock()' use does result in very ugly header files,
and requires you to basically wrap the real function with that macro
that uses '__cond_lock'. Which has made PeterZ NAK things that try to
fix sparse warnings over the years [1].
To solve this, there is now a very experimental patch to sparse that
basically does the exact same thing as '__cond_lock()' did, but using a
function attribute instead. That seems to make PeterZ happy [2].
Note that this does not replace existing use of '__cond_lock()', but
only exposes the new proposed attribute and uses it for the previously
unannotated 'refcount_dec_and_lock()' family of functions.
For existing sparse installations, this will make no difference (a
negative output context was ignored), but if you have the experimental
sparse patch it will make sparse now understand code that uses those
functions, the same way '__cond_lock()' makes sparse understand the very
similar 'atomic_dec_and_lock()' uses that have the old '__cond_lock()'
annotations.
Note that in some cases this will silence existing context imbalance
warnings. But in other cases it may end up exposing new sparse warnings
for code that sparse just didn't see the locking for at all before.
This is a trial, in other words. I'd expect that if it ends up being
successful, and new sparse releases end up having this new attribute,
we'll migrate the old-style '__cond_lock()' users to use the new-style
'__cond_acquires' function attribute.
The actual experimental sparse patch was posted in [3].
Link: https://lore.kernel.org/all/20130930134434.GC12926@twins.programming.kicks-ass.net/ [1]
Link: https://lore.kernel.org/all/Yr60tWxN4P568x3W@worktop.programming.kicks-ass.net/ [2]
Link: https://lore.kernel.org/all/CAHk-=wjZfO9hGqJ2_hGQG3U_XzSh9_XaXze=HgPdvJbgrvASfA@mail.gmail.com/ [3]
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Alexander Aring <aahringo@redhat.com>
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- Fix statfs blocking on background inode gc workers
- Fix some broken inode lock assertion code
- Fix xattr leaf buffer leaks when cancelling a deferred xattr update
operation
- Clean up xattr recovery to make it easier to understand.
- Fix xattr leaf block verifiers tripping over empty blocks.
- Remove complicated and error prone xattr leaf block bholding mess.
- Fix a bug where an rt extent crossing EOF was treated as "posteof"
blocks and cleaned unnecessarily.
- Fix a UAF when log shutdown races with unmount.
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Merge tag 'xfs-5.19-fixes-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux
Pull xfs fixes from Darrick Wong:
"This fixes some stalling problems and corrects the last of the
problems (I hope) observed during testing of the new atomic xattr
update feature.
- Fix statfs blocking on background inode gc workers
- Fix some broken inode lock assertion code
- Fix xattr leaf buffer leaks when cancelling a deferred xattr update
operation
- Clean up xattr recovery to make it easier to understand.
- Fix xattr leaf block verifiers tripping over empty blocks.
- Remove complicated and error prone xattr leaf block bholding mess.
- Fix a bug where an rt extent crossing EOF was treated as "posteof"
blocks and cleaned unnecessarily.
- Fix a UAF when log shutdown races with unmount"
* tag 'xfs-5.19-fixes-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
xfs: prevent a UAF when log IO errors race with unmount
xfs: dont treat rt extents beyond EOF as eofblocks to be cleared
xfs: don't hold xattr leaf buffers across transaction rolls
xfs: empty xattr leaf header blocks are not corruption
xfs: clean up the end of xfs_attri_item_recover
xfs: always free xattri_leaf_bp when cancelling a deferred op
xfs: use invalidate_lock to check the state of mmap_lock
xfs: factor out the common lock flags assert
xfs: introduce xfs_inodegc_push()
xfs: bound maximum wait time for inodegc work
