Commit Graph

337 Commits

Author SHA1 Message Date
Trond Myklebust
59464b262f SUNRPC: SOFTCONN tasks should time out when on the sending list
SOFTCONN tasks need to periodically check if the transport is still
connected, so that they can time out if that is not the case.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2023-10-22 19:47:57 -04:00
Thomas Gleixner
9a5a305686 timers: Get rid of del_singleshot_timer_sync()
del_singleshot_timer_sync() used to be an optimization for deleting timers
which are not rearmed from the timer callback function.

This optimization turned out to be broken and got mapped to
del_timer_sync() about 17 years ago.

Get rid of the undocumented indirection and use del_timer_sync() directly.

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Link: https://lore.kernel.org/r/20221123201624.706987932@linutronix.de
2022-11-24 15:09:10 +01:00
Linus Torvalds
f1947d7c8a Random number generator fixes for Linux 6.1-rc1.
-----BEGIN PGP SIGNATURE-----
 
 iQIzBAABCAAdFiEEq5lC5tSkz8NBJiCnSfxwEqXeA64FAmNHYD0ACgkQSfxwEqXe
 A655AA//dJK0PdRghqrKQsl18GOCffV5TUw5i1VbJQbI9d8anfxNjVUQiNGZi4et
 qUwZ8OqVXxYx1Z1UDgUE39PjEDSG9/cCvOpMUWqN20/+6955WlNZjwA7Fk6zjvlM
 R30fz5CIJns9RFvGT4SwKqbVLXIMvfg/wDENUN+8sxt36+VD2gGol7J2JJdngEhM
 lW+zqzi0ABqYy5so4TU2kixpKmpC08rqFvQbD1GPid+50+JsOiIqftDErt9Eg1Mg
 MqYivoFCvbAlxxxRh3+UHBd7ZpJLtp1UFEOl2Rf00OXO+ZclLCAQAsTczucIWK9M
 8LCZjb7d4lPJv9RpXFAl3R1xvfc+Uy2ga5KeXvufZtc5G3aMUKPuIU7k28ZyblVS
 XXsXEYhjTSd0tgi3d0JlValrIreSuj0z2QGT5pVcC9utuAqAqRIlosiPmgPlzXjr
 Us4jXaUhOIPKI+Musv/fqrxsTQziT0jgVA3Njlt4cuAGm/EeUbLUkMWwKXjZLTsv
 vDsBhEQFmyZqxWu4pYo534VX2mQWTaKRV1SUVVhQEHm57b00EAiZohoOvweB09SR
 4KiJapikoopmW4oAUFotUXUL1PM6yi+MXguTuc1SEYuLz/tCFtK8DJVwNpfnWZpE
 lZKvXyJnHq2Sgod/hEZq58PMvT6aNzTzSg7YzZy+VabxQGOO5mc=
 =M+mV
 -----END PGP SIGNATURE-----

Merge tag 'random-6.1-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random

Pull more random number generator updates from Jason Donenfeld:
 "This time with some large scale treewide cleanups.

  The intent of this pull is to clean up the way callers fetch random
  integers. The current rules for doing this right are:

   - If you want a secure or an insecure random u64, use get_random_u64()

   - If you want a secure or an insecure random u32, use get_random_u32()

     The old function prandom_u32() has been deprecated for a while
     now and is just a wrapper around get_random_u32(). Same for
     get_random_int().

   - If you want a secure or an insecure random u16, use get_random_u16()

   - If you want a secure or an insecure random u8, use get_random_u8()

   - If you want secure or insecure random bytes, use get_random_bytes().

     The old function prandom_bytes() has been deprecated for a while
     now and has long been a wrapper around get_random_bytes()

   - If you want a non-uniform random u32, u16, or u8 bounded by a
     certain open interval maximum, use prandom_u32_max()

     I say "non-uniform", because it doesn't do any rejection sampling
     or divisions. Hence, it stays within the prandom_*() namespace, not
     the get_random_*() namespace.

     I'm currently investigating a "uniform" function for 6.2. We'll see
     what comes of that.

  By applying these rules uniformly, we get several benefits:

   - By using prandom_u32_max() with an upper-bound that the compiler
     can prove at compile-time is ≤65536 or ≤256, internally
     get_random_u16() or get_random_u8() is used, which wastes fewer
     batched random bytes, and hence has higher throughput.

   - By using prandom_u32_max() instead of %, when the upper-bound is
     not a constant, division is still avoided, because
     prandom_u32_max() uses a faster multiplication-based trick instead.

   - By using get_random_u16() or get_random_u8() in cases where the
     return value is intended to indeed be a u16 or a u8, we waste fewer
     batched random bytes, and hence have higher throughput.

  This series was originally done by hand while I was on an airplane
  without Internet. Later, Kees and I worked on retroactively figuring
  out what could be done with Coccinelle and what had to be done
  manually, and then we split things up based on that.

  So while this touches a lot of files, the actual amount of code that's
  hand fiddled is comfortably small"

* tag 'random-6.1-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random:
  prandom: remove unused functions
  treewide: use get_random_bytes() when possible
  treewide: use get_random_u32() when possible
  treewide: use get_random_{u8,u16}() when possible, part 2
  treewide: use get_random_{u8,u16}() when possible, part 1
  treewide: use prandom_u32_max() when possible, part 2
  treewide: use prandom_u32_max() when possible, part 1
2022-10-16 15:27:07 -07:00
Jason A. Donenfeld
a251c17aa5 treewide: use get_random_u32() when possible
The prandom_u32() function has been a deprecated inline wrapper around
get_random_u32() for several releases now, and compiles down to the
exact same code. Replace the deprecated wrapper with a direct call to
the real function. The same also applies to get_random_int(), which is
just a wrapper around get_random_u32(). This was done as a basic find
and replace.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz> # for ext4
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk> # for sch_cake
Acked-by: Chuck Lever <chuck.lever@oracle.com> # for nfsd
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com> # for thunderbolt
Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs
Acked-by: Helge Deller <deller@gmx.de> # for parisc
Acked-by: Heiko Carstens <hca@linux.ibm.com> # for s390
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2022-10-11 17:42:58 -06:00
Ziyang Xuan
d6abc719a2 SUNRPC: use max_t() to simplify open code
Use max_t() to simplify open code which uses "if...else" to get maximum of
two values.

Generated by coccinelle script:
	scripts/coccinelle/misc/minmax.cocci

Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2022-10-03 11:26:36 -04:00
Bo Liu
9947e57b22 SUNRPC: Directly use ida_alloc()/free()
Use ida_alloc()/ida_free() instead of
ida_simple_get()/ida_simple_remove().
The latter is deprecated and more verbose.

Signed-off-by: Bo Liu <liubo03@inspur.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2022-10-03 11:26:36 -04:00
Trond Myklebust
17814819ac SUNRPC: Fix call completion races with call_decode()
We need to make sure that the req->rq_private_buf is completely up to
date before we make req->rq_reply_bytes_recvd visible to the
call_decode() routine in order to avoid triggering the WARN_ON().

Reported-by: Benjamin Coddington <bcodding@redhat.com>
Fixes: 72691a269f ("SUNRPC: Don't reuse bvec on retransmission of the request")
Tested-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2022-09-01 10:40:37 -04:00
Trond Myklebust
72691a269f SUNRPC: Don't reuse bvec on retransmission of the request
If a request is re-encoded and then retransmitted, we need to make sure
that we also re-encode the bvec, in case the page lists have changed.

Fixes: ff053dbbaf ("SUNRPC: Move the call to xprt_send_pagedata() out of xprt_sock_sendmsg()")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2022-07-27 16:26:17 -04:00
Olga Kornievskaia
497e6464d6 SUNRPC create an rpc function that allows xprt removal from rpc_clnt
Expose a function that allows a removal of xprt from the rpc_clnt.

When called from NFS that's running a trunked transport then don't
decrement the active transport counter.

Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2022-07-25 10:06:04 -04:00
Olga Kornievskaia
7ffcdaa670 SUNRPC expose functions for offline remote xprt functionality
Re-arrange the code that make offline transport and delete transport
callable functions.

Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2022-07-25 10:06:04 -04:00
Linus Torvalds
1a3b1bba7c NFS client bugfixes for Linux 5.18
Highlights include:
 
 Stable fixes:
 - SUNRPC: Ensure we flush any closed sockets before xs_xprt_free()
 
 Bugfixes:
 - Fix an Oopsable condition due to SLAB_ACCOUNT setting in the NFSv4.2
   xattr code.
 - Fix for open() using an file open mode of '3' in NFSv4
 - Replace readdir's use of xxhash() with hash_64()
 - Several patches to handle malloc() failure in SUNRPC
 -----BEGIN PGP SIGNATURE-----
 
 iQIzBAABCAAdFiEESQctxSBg8JpV8KqEZwvnipYKAPIFAmJQb5IACgkQZwvnipYK
 APLVeRAAheQX422gIrjrWsQrZxJWmMDBBj9qwiV14XMs6g5KF/DtNbIJm1BGjA9Y
 aLgNVknSDcGHMmvdh5MCVF7R61sqkCNbQWP3Bx6OBP6ei3FEgQBPyujcFXAaZ7UK
 T4fBzfPoEYaxVkEG/L5BsAUnh6TvyCfNm1oqZZv2bv9M0U6UlXnRLWZN9I6cAtcw
 GI9HgnufWOxJWIqPd9dY45aF44Ru+aJ953eecPh0G83Reoc99EAU+PvJJD18Wl0H
 BZqM6ar5pNush50yVIjnPFXg+sM97dKGlLvYL11Uy7f8valSaBXPZLZQ/jG4Vx/a
 m/l8FVwBEV89BG7z6jKNju7ERbO+xbPgXP8lSwkj69fXOpuvzo/G6VAxS6ZJww12
 p6TJnhCMSEF7qrQc5mejA803dT4MiJWo4i2th482Ws/tRN5H+y9pDYLsvBPM8iHo
 sVkJBco04tBHEH3qKgDTu8EY7/shH+GVO3Wmtcjz47T2rbmQB7gJtfipHcLmV2qd
 Jy1tiz1T7rhGs7KNtWpu8210MY9iFhIt3rAvdGdeVmgnNjrmRex0Sxqx8vgKUAFE
 aQjXkkpwHA3rHWnuGPMKu5i48BPFQ8m4QgdVC9F6ylNT6RIbImqplQiwIYNIxYC+
 cBohUG1yYZRjFEMkXBdfK5cImkTLW7RkLCatRh5v8OU8xqpRVL8=
 =edfs
 -----END PGP SIGNATURE-----

Merge tag 'nfs-for-5.18-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs

Pull NFS client fixes from Trond Myklebust:
 "Stable fixes:

   - SUNRPC: Ensure we flush any closed sockets before xs_xprt_free()

  Bugfixes:

   - Fix an Oopsable condition due to SLAB_ACCOUNT setting in the
     NFSv4.2 xattr code.

   - Fix for open() using an file open mode of '3' in NFSv4

   - Replace readdir's use of xxhash() with hash_64()

   - Several patches to handle malloc() failure in SUNRPC"

* tag 'nfs-for-5.18-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  SUNRPC: Move the call to xprt_send_pagedata() out of xprt_sock_sendmsg()
  SUNRPC: svc_tcp_sendmsg() should handle errors from xdr_alloc_bvec()
  SUNRPC: Handle allocation failure in rpc_new_task()
  NFS: Ensure rpc_run_task() cannot fail in nfs_async_rename()
  NFSv4/pnfs: Handle RPC allocation errors in nfs4_proc_layoutget
  SUNRPC: Handle low memory situations in call_status()
  SUNRPC: Handle ENOMEM in call_transmit_status()
  NFSv4.2: Fix missing removal of SLAB_ACCOUNT on kmem_cache allocation
  SUNRPC: Ensure we flush any closed sockets before xs_xprt_free()
  NFS: Replace readdir's use of xxhash() with hash_64()
  SUNRPC: handle malloc failure in ->request_prepare
  NFSv4: fix open failure with O_ACCMODE flag
  Revert "NFSv4: Handle the special Linux file open access mode"
2022-04-08 07:39:17 -10:00
Trond Myklebust
f00432063d SUNRPC: Ensure we flush any closed sockets before xs_xprt_free()
We must ensure that all sockets are closed before we call xprt_free()
and release the reference to the net namespace. The problem is that
calling fput() will defer closing the socket until delayed_fput() gets
called.
Let's fix the situation by allowing rpciod and the transport teardown
code (which runs on the system wq) to call __fput_sync(), and directly
close the socket.

Reported-by: Felix Fu <foyjog@gmail.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Fixes: a73881c96d ("SUNRPC: Fix an Oops in udp_poll()")
Cc: stable@vger.kernel.org # 5.1.x: 3be232f11a: SUNRPC: Prevent immediate close+reconnect
Cc: stable@vger.kernel.org # 5.1.x: 89f42494f9: SUNRPC: Don't call connect() more than once on a TCP socket
Cc: stable@vger.kernel.org # 5.1.x
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2022-04-07 16:19:47 -04:00
NeilBrown
eb07d5a4da SUNRPC: handle malloc failure in ->request_prepare
If ->request_prepare() detects an error, it sets ->rq_task->tk_status.
This is easy for callers to ignore.
The only caller is xprt_request_enqueue_receive() and it does ignore the
error, as does call_encode() which calls it.  This can result in a
request being queued to receive a reply without an allocated receive buffer.

So instead of setting rq_task->tk_status, return an error, and store in
->tk_status only in call_encode();

The call to xprt_request_enqueue_receive() is now earlier in
call_encode(), where the error can still be handled.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2022-03-29 22:15:46 -04:00
Linus Torvalds
965181d7ef NFS client updates for Linux 5.18
Highlights include:
 
 Features:
 - Switch NFS to use readahead instead of the obsolete readpages.
 - Readdir fixes to improve cacheability of large directories when there
   are multiple readers and writers.
 - Readdir performance improvements when doing a seekdir() immediately
   after opening the directory (common when re-exporting NFS).
 - NFS swap improvements from Neil Brown.
 - Loosen up memory allocation to permit direct reclaim and write back
   in cases where there is no danger of deadlocking the writeback code or
   NFS swap.
 - Avoid sillyrename when the NFSv4 server claims to support the
   necessary features to recover the unlinked but open file after reboot.
 
 Bugfixes:
 - Patch from Olga to add a mount option to control NFSv4.1 session
   trunking discovery, and default it to being off.
 - Fix a lockup in nfs_do_recoalesce().
 - Two fixes for list iterator variables being used when pointing to the
   list head.
 - Fix a kernel memory scribble when reading from a non-socket transport
   in /sys/kernel/sunrpc.
 - Fix a race where reconnecting to a server could leave the TCP socket
   stuck forever in the connecting state.
 - Patch from Neil to fix a shutdown race which can leave the SUNRPC
   transport timer primed after we free the struct xprt itself.
 - Patch from Xin Xiong to fix reference count leaks in the NFSv4.2 copy
   offload.
 - Sunrpc patch from Olga to avoid resending a task on an offlined
   transport.
 
 Cleanups:
 - Patches from Dave Wysochanski to clean up the fscache code
 -----BEGIN PGP SIGNATURE-----
 
 iQIzBAABCAAdFiEESQctxSBg8JpV8KqEZwvnipYKAPIFAmJDLLUACgkQZwvnipYK
 APJZ5Q/9FH5S38RcUOxpFS+XaVdmxltJTMQv9Bz5mcyljq6PwRjTn73Qs7MfBQfD
 k90O9Pn/EXgQpFWNW4o/saQGLAO1MbVaesdNNF92Le9NziMz7lr95fsFXOqpg9EQ
 rEVOImWinv/N0+P0yv5tgjx6Fheu70L4dnwsxepnmtv2R1VjXOVchK7WjsV+9qey
 Xvn15OzhtVCGhRvvKfmGuGW+2I0D29tRNn2X0Pi+LjxAEQ0We/rcsJeGDMGYtbeC
 2U4ADk7KB0kJq04WYCH8k8tTrljL3PUONzO6QP1lltmAZ0FOwXf/AjyaD3SML2Xu
 A1yc2bEn3/S6wCQ3BiMxoE7UCSewg/ZyQD7B9GjZ/nWYNXREhLKvtVZt+ULTCA6o
 UKAI2vlEHljzQI2YfbVVZFyL8KCZqi+BFcJ/H/dtFKNazIkiefkaF+703Pflazis
 HjhA5G6IT0Pk6qZ6OBp+Z/4kCDYZYXXi9ysiNuMPWCiYEfZzt7ocUjm44uRAi+vR
 Qpf0V01Rg4iplTj3YFXqb9TwxrudzC7AcQ7hbLJia0kD/8djG+aGZs3SJWeO+VuE
 Xa41oxAx9jqOSRvSKPvj7nbexrwn8PtQI2NtDRqjPXlg6+Jbk23u8lIEVhsCH877
 xoMUHtTKLyqECskzRN4nh7qoBD3QfiLuI74aDcPtGEuXzU1+Ox8=
 =jeGt
 -----END PGP SIGNATURE-----

Merge tag 'nfs-for-5.18-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs

Pull NFS client updates from Trond Myklebust:
 "Highlights include:

  Features:

   - Switch NFS to use readahead instead of the obsolete readpages.

   - Readdir fixes to improve cacheability of large directories when
     there are multiple readers and writers.

   - Readdir performance improvements when doing a seekdir() immediately
     after opening the directory (common when re-exporting NFS).

   - NFS swap improvements from Neil Brown.

   - Loosen up memory allocation to permit direct reclaim and write back
     in cases where there is no danger of deadlocking the writeback code
     or NFS swap.

   - Avoid sillyrename when the NFSv4 server claims to support the
     necessary features to recover the unlinked but open file after
     reboot.

  Bugfixes:

   - Patch from Olga to add a mount option to control NFSv4.1 session
     trunking discovery, and default it to being off.

   - Fix a lockup in nfs_do_recoalesce().

   - Two fixes for list iterator variables being used when pointing to
     the list head.

   - Fix a kernel memory scribble when reading from a non-socket
     transport in /sys/kernel/sunrpc.

   - Fix a race where reconnecting to a server could leave the TCP
     socket stuck forever in the connecting state.

   - Patch from Neil to fix a shutdown race which can leave the SUNRPC
     transport timer primed after we free the struct xprt itself.

   - Patch from Xin Xiong to fix reference count leaks in the NFSv4.2
     copy offload.

   - Sunrpc patch from Olga to avoid resending a task on an offlined
     transport.

  Cleanups:

   - Patches from Dave Wysochanski to clean up the fscache code"

* tag 'nfs-for-5.18-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs: (91 commits)
  NFSv4/pNFS: Fix another issue with a list iterator pointing to the head
  NFS: Don't loop forever in nfs_do_recoalesce()
  SUNRPC: Don't return error values in sysfs read of closed files
  SUNRPC: Do not dereference non-socket transports in sysfs
  NFSv4.1: don't retry BIND_CONN_TO_SESSION on session error
  SUNRPC don't resend a task on an offlined transport
  NFS: replace usage of found with dedicated list iterator variable
  SUNRPC: avoid race between mod_timer() and del_timer_sync()
  pNFS/files: Ensure pNFS allocation modes are consistent with nfsiod
  pNFS/flexfiles: Ensure pNFS allocation modes are consistent with nfsiod
  NFSv4/pnfs: Ensure pNFS allocation modes are consistent with nfsiod
  NFS: Avoid writeback threads getting stuck in mempool_alloc()
  NFS: nfsiod should not block forever in mempool_alloc()
  SUNRPC: Make the rpciod and xprtiod slab allocation modes consistent
  SUNRPC: Fix unx_lookup_cred() allocation
  NFS: Fix memory allocation in rpc_alloc_task()
  NFS: Fix memory allocation in rpc_malloc()
  SUNRPC: Improve accuracy of socket ENOBUFS determination
  SUNRPC: Replace internal use of SOCKWQ_ASYNC_NOSPACE
  SUNRPC: Fix socket waits for write buffer space
  ...
2022-03-29 18:55:37 -07:00
NeilBrown
3848e96edf SUNRPC: avoid race between mod_timer() and del_timer_sync()
xprt_destory() claims XPRT_LOCKED and then calls del_timer_sync().
Both xprt_unlock_connect() and xprt_release() call
 ->release_xprt()
which drops XPRT_LOCKED and *then* xprt_schedule_autodisconnect()
which calls mod_timer().

This may result in mod_timer() being called *after* del_timer_sync().
When this happens, the timer may fire long after the xprt has been freed,
and run_timer_softirq() will probably crash.

The pairing of ->release_xprt() and xprt_schedule_autodisconnect() is
always called under ->transport_lock.  So if we take ->transport_lock to
call del_timer_sync(), we can be sure that mod_timer() will run first
(if it runs at all).

Cc: stable@vger.kernel.org
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2022-03-23 14:50:04 -04:00
Trond Myklebust
b2648015d4 SUNRPC: Make the rpciod and xprtiod slab allocation modes consistent
Make sure that rpciod and xprtiod are always using the same slab
allocation modes.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2022-03-22 15:52:55 -04:00
NeilBrown
8db55a032a SUNRPC: improve 'swap' handling: scheduling and PF_MEMALLOC
rpc tasks can be marked as RPC_TASK_SWAPPER.  This causes GFP_MEMALLOC
to be used for some allocations.  This is needed in some cases, but not
in all where it is currently provided, and in some where it isn't
provided.

Currently *all* tasks associated with a rpc_client on which swap is
enabled get the flag and hence some GFP_MEMALLOC support.

GFP_MEMALLOC is provided for ->buf_alloc() but only swap-writes need it.
However xdr_alloc_bvec does not get GFP_MEMALLOC - though it often does
need it.

xdr_alloc_bvec is called while the XPRT_LOCK is held.  If this blocks,
then it blocks all other queued tasks.  So this allocation needs
GFP_MEMALLOC for *all* requests, not just writes, when the xprt is used
for any swap writes.

Similarly, if the transport is not connected, that will block all
requests including swap writes, so memory allocations should get
GFP_MEMALLOC if swap writes are possible.

So with this patch:
 1/ we ONLY set RPC_TASK_SWAPPER for swap writes.
 2/ __rpc_execute() sets PF_MEMALLOC while handling any task
    with RPC_TASK_SWAPPER set, or when handling any task that
    holds the XPRT_LOCKED lock on an xprt used for swap.
    This removes the need for the RPC_IS_SWAPPER() test
    in ->buf_alloc handlers.
 3/ xprt_prepare_transmit() sets PF_MEMALLOC after locking
    any task to a swapper xprt.  __rpc_execute() will clear it.
 3/ PF_MEMALLOC is set for all the connect workers.

Reviewed-by: Chuck Lever <chuck.lever@oracle.com> (for xprtrdma parts)
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2022-03-13 12:59:35 -04:00
NeilBrown
a80a846186 SUNRPC: remove scheduling boost for "SWAPPER" tasks.
Currently, tasks marked as "swapper" tasks get put to the front of
non-priority rpc_queues, and are sorted earlier than non-swapper tasks on
the transport's ->xmit_queue.

This is pointless as currently *all* tasks for a mount that has swap
enabled on *any* file are marked as "swapper" tasks.  So the net result
is that the non-priority rpc_queues are reverse-ordered (LIFO).

This scheduling boost is not necessary to avoid deadlocks, and hurts
fairness, so remove it.  If there were a need to expedite some requests,
the tk_priority mechanism is a more appropriate tool.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2022-03-13 12:59:35 -04:00
NeilBrown
a721035477 SUNRPC/xprt: async tasks mustn't block waiting for memory
When memory is short, new worker threads cannot be created and we depend
on the minimum one rpciod thread to be able to handle everything.  So it
must not block waiting for memory.

xprt_dynamic_alloc_slot can block indefinitely.  This can tie up all
workqueue threads and NFS can deadlock.  So when called from a
workqueue, set __GFP_NORETRY.

The rdma alloc_slot already does not block.  However it sets the error
to -EAGAIN suggesting this will trigger a sleep.  It does not.  As we
can see in call_reserveresult(), only -ENOMEM causes a sleep.  -EAGAIN
causes immediate retry.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2022-03-13 12:59:35 -04:00
Trond Myklebust
0adc879406 SUNRPC: Convert GFP_NOFS to GFP_KERNEL
The sections which should not re-enter the filesystem are already
protected with memalloc_nofs_save/restore calls, so it is better to use
GFP_KERNEL in these calls to allow better performance for synchronous
RPC calls.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2022-02-25 18:50:12 -05:00
Eric Dumazet
b9a0d6d143 SUNRPC: add netns refcount tracker to struct rpc_xprt
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-01-28 14:47:55 +00:00
Trond Myklebust
3be232f11a SUNRPC: Prevent immediate close+reconnect
If we have already set up the socket and are waiting for it to connect,
then don't immediately close and retry.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2021-11-04 19:46:19 -04:00
Trond Myklebust
d896ba8300 SUNRPC: Fix races when closing the socket
Ensure that we bump the xprt->connect_cookie when we set the
XPRT_CLOSE_WAIT flag so that another call to
xprt_conditional_disconnect() won't race with the reconnection.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2021-11-04 19:46:19 -04:00
Trond Myklebust
33c3214bf4 SUNRPC: xprt_clear_locked() only needs release memory semantics
The clearing of the XPRT_LOCKED bit has to happen after we clear
xprt->snd_task, but we don't require any extra memory barriers after
that.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2021-10-03 20:49:06 -04:00
Trond Myklebust
ea7a1019d8 SUNRPC: Partial revert of commit 6f9f17287e
The premise of commit 6f9f17287e ("SUNRPC: Mitigate cond_resched() in
xprt_transmit()") was that cond_resched() is expensive and unnecessary
when there has been just a single send.
The point of cond_resched() is to ensure that tasks that should pre-empt
this one get a chance to do so when it is safe to do so. The code prior
to commit 6f9f17287e failed to take into account that it was keeping a
rpc_task pinned for longer than it needed to, and so rather than doing a
full revert, let's just move the cond_resched.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2021-10-03 20:49:05 -04:00
Linus Torvalds
0961f0c00e NFS Client Updates for Linux 5.15
- New Features:
   - Better client responsiveness when server isn't replying
   - Use refcount_t in sunrpc rpc_client refcount tracking
   - Add srcaddr and dst_port to the sunrpc sysfs info files
   - Add basic support for connection sharing between servers with multiple NICs`
 
 - Bugfixes and Cleanups:
   - Sunrpc tracepoint cleanups
   - Disconnect after ib_post_send() errors to avoid deadlocks
   - Fix for tearing down rpcrdma_reps
   - Fix a potential pNFS layoutget livelock loop
   - pNFS layout barrier fixes
   - Fix a potential memory corruption in rpc_wake_up_queued_task_set_status()
   - Fix reconnection locking
   - Fix return value of get_srcport()
   - Remove rpcrdma_post_sends()
   - Remove pNFS dead code
   - Remove copy size restriction for inter-server copies
   - Overhaul the NFS callback service
   - Clean up sunrpc TCP socket shutdowns
   - Always provide aligned buffers to RPC read layers
 -----BEGIN PGP SIGNATURE-----
 
 iQIyBAABCAAdFiEEnZ5MQTpR7cLU7KEp18tUv7ClQOsFAmExP7AACgkQ18tUv7Cl
 QOshTg/zBz7OfrS23CcLLgNidTJ6S7JOuj1DShG+YzsYXT8f9Nl1DadLM7yAEyok
 6JZzC8rXYzJcmYztHZzRyTuzj1+tGGb0u/MrD0bBk42VEel6eOjH/Y9ybn12Gf/E
 aqlcJh8hPx44U8oo5EFjRJsg2h28O06vywqhJz+sTbkqKN4hlAgMOo5ysAB+1thg
 BrTlR84EKBw5QqxPJ1WPmq9tEyGebU9Yrj1p8f0Uf015IeRNeTOXx3NzmdPshphf
 2yJvjumwEzqkcHXTJFDfP6ikIcGPPMNVAOK8DHb+vDGzNsOXW7dDM7GuWA3U8DlU
 ZHvyyb05Wwe6Wwg8xwx90FEXcYZFfZbSKmI9z2uoOuGFzNG07zWzPDzRft+qrOvU
 VMMwP9oEh71+qesmWTvqIbR2RjxqbCYlTcc8mBrD66DROi6jZ2jznraNC85sxG0Q
 b8GE+2SnYr2Q25yehj2xrRlOXyiYNkeeYmIpIquEqH9o7cSyDNJhBWbzIv6x+ith
 O/S06ZVKMc9X1nH5t5121XcHrSTMMVA/67WMyKfKMxWnrADAWPQALG+ttoTcbRu7
 Txew3Jb+hB8+ZdHAqbPf1l1i+7USQl1CRHMw3GRvNjCL2qcjZb1R7eyJRSQQtUyw
 q6SJRGe6Sn1FTUnn96Hv15Zy8VHx+q0cOL/EQVzL1RzJIXYcag==
 =Ad/3
 -----END PGP SIGNATURE-----

Merge tag 'nfs-for-5.15-1' of git://git.linux-nfs.org/projects/anna/linux-nfs

Pull NFS client updates from Anna Schumaker:
 "New Features:
   - Better client responsiveness when server isn't replying
   - Use refcount_t in sunrpc rpc_client refcount tracking
   - Add srcaddr and dst_port to the sunrpc sysfs info files
   - Add basic support for connection sharing between servers with multiple NICs`

  Bugfixes and Cleanups:
   - Sunrpc tracepoint cleanups
   - Disconnect after ib_post_send() errors to avoid deadlocks
   - Fix for tearing down rpcrdma_reps
   - Fix a potential pNFS layoutget livelock loop
   - pNFS layout barrier fixes
   - Fix a potential memory corruption in rpc_wake_up_queued_task_set_status()
   - Fix reconnection locking
   - Fix return value of get_srcport()
   - Remove rpcrdma_post_sends()
   - Remove pNFS dead code
   - Remove copy size restriction for inter-server copies
   - Overhaul the NFS callback service
   - Clean up sunrpc TCP socket shutdowns
   - Always provide aligned buffers to RPC read layers"

* tag 'nfs-for-5.15-1' of git://git.linux-nfs.org/projects/anna/linux-nfs: (39 commits)
  NFS: Always provide aligned buffers to the RPC read layers
  NFSv4.1 add network transport when session trunking is detected
  SUNRPC enforce creation of no more than max_connect xprts
  NFSv4 introduce max_connect mount options
  SUNRPC add xps_nunique_destaddr_xprts to xprt_switch_info in sysfs
  SUNRPC keep track of number of transports to unique addresses
  NFSv3: Delete duplicate judgement in nfs3_async_handle_jukebox
  SUNRPC: Tweak TCP socket shutdown in the RPC client
  SUNRPC: Simplify socket shutdown when not reusing TCP ports
  NFSv4.2: remove restriction of copy size for inter-server copy.
  NFS: Clean up the synopsis of callback process_op()
  NFS: Extract the xdr_init_encode/decode() calls from decode_compound
  NFS: Remove unused callback void decoder
  NFS: Add a private local dispatcher for NFSv4 callback operations
  SUNRPC: Eliminate the RQ_AUTHERR flag
  SUNRPC: Set rq_auth_stat in the pg_authenticate() callout
  SUNRPC: Add svc_rqst::rq_auth_stat
  SUNRPC: Add dst_port to the sysfs xprt info file
  SUNRPC: Add srcaddr as a file in sysfs
  sunrpc: Fix return value of get_srcport()
  ...
2021-09-04 10:25:26 -07:00
Chuck Lever
a4ae308143 SUNRPC: Move client-side disconnect injection
Disconnect injection stress-tests the ability for both client and
server implementations to behave resiliently in the face of network
instability.

Convert the existing client-side disconnect injection infrastructure
to use the kernel's generic error injection facility. The generic
facility has a richer set of injection criteria.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2021-08-20 13:50:32 -04:00
Trond Myklebust
f99fa50880 SUNRPC/xprtrdma: Fix reconnection locking
The xprtrdma client code currently relies on the task that initiated the
connect to hold the XPRT_LOCK for the duration of the connection
attempt. If the task is woken early, due to some other event, then that
lock could get released early.
Avoid races by using the same mechanism that the socket code uses of
transferring lock ownership to the RDMA connect worker itself. That
frees us to call rpcrdma_xprt_disconnect() directly since we're now
guaranteed exclusion w.r.t. other callers.

Fixes: 4cf44be6f1 ("xprtrdma: Fix recursion into rpcrdma_xprt_disconnect()")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2021-08-09 16:57:05 -04:00
Trond Myklebust
e26d997272 SUNRPC: Clean up scheduling of autoclose
Consolidate duplicated code in xprt_force_disconnect() and
xprt_conditional_disconnect().

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2021-08-09 16:57:05 -04:00
Trond Myklebust
c2dc3e5fad SUNRPC: Fix potential memory corruption
We really should not call rpc_wake_up_queued_task_set_status() with
xprt->snd_task as an argument unless we are certain that is actually an
rpc_task.

Fixes: 0445f92c5d ("SUNRPC: Fix disconnection races")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2021-08-09 16:57:05 -04:00
Olga Kornievskaia
587bc7255d sunrpc: add dst_attr attributes to the sysfs xprt directory
Allow to query and set the destination's address of a transport.
Setting of the destination address is allowed only for TCP or RDMA
based connections.

Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2021-07-08 14:03:24 -04:00
Olga Kornievskaia
572caba402 sunrpc: add xprt id
This adds a unique identifier for a sunrpc transport in sysfs, which is
similarly managed to the unique IDs of clients.

Signed-off-by: Dan Aloni <dan@kernelim.com>
Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2021-07-08 14:03:23 -04:00
Trond Myklebust
e86be3a04b SUNRPC: More fixes for backlog congestion
Ensure that we fix the XPRT_CONGESTED starvation issue for RDMA as well
as socket based transports.
Ensure we always initialise the request after waking up from the backlog
list.

Fixes: e877a88d1f ("SUNRPC in case of backlog, hand free slots directly to waiting task")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2021-05-26 06:36:13 -04:00
NeilBrown
e877a88d1f SUNRPC in case of backlog, hand free slots directly to waiting task
If sunrpc.tcp_max_slot_table_entries is small and there are tasks
on the backlog queue, then when a request completes it is freed and the
first task on the queue is woken.  The expectation is that it will wake
and claim that request.  However if it was a sync task and the waiting
process was killed at just that moment, it will wake and NOT claim the
request.

As long as TASK_CONGESTED remains set, requests can only be claimed by
tasks woken from the backlog, and they are woken only as requests are
freed, so when a task doesn't claim a request, no other task can ever
get that request until TASK_CONGESTED is cleared.  Each time this
happens the number of available requests is decreased by one.

With a sufficiently high workload and sufficiently low setting of
max_slot (16 in the case where this was seen), TASK_CONGESTED can remain
set for an extended period, and the above scenario (of a process being
killed just as its task was woken) can repeat until no requests can be
allocated.  Then traffic stops.

This patch addresses the problem by introducing a positive handover of a
request from a completing task to a backlog task - the request is never
freed when there is a backlog.

When a task is woken it might not already have a request attached in
which case it is *not* freed (as with current code) but is initialised
(if needed) and used.  If it isn't used it will eventually be freed by
rpc_exit_task().  xprt_release() is enhanced to be able to correctly
release an uninitialised request.

Fixes: ba60eb25ff ("SUNRPC: Fix a livelock problem in the xprt->backlog queue")
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2021-05-20 12:17:08 -04:00
Chris Dion
09252177d5 SUNRPC: Handle major timeout in xprt_adjust_timeout()
Currently if a major timeout value is reached, but the minor value has
not been reached, an ETIMEOUT will not be sent back to the caller.
This can occur if the v4 server is not responding to requests and
retrans is configured larger than the default of two.

For example, A TCP mount with a configured timeout value of 50 and a
retransmission count of 3 to a v4 server which is not responding:

1. Initial value and increment set to 5s, maxval set to 20s, retries at 3
2. Major timeout is set to 20s, minor timeout set to 5s initially
3. xport_adjust_timeout() is called after 5s, retry with 10s timeout,
   minor timeout is bumped to 10s
4. And again after another 10s, 15s total time with minor timeout set
   to 15s
5. After 20s total time xport_adjust_timeout is called as major timeout is
   reached, but skipped because the minor timeout is not reached
       - After this time the cpu spins continually calling
       	 xport_adjust_timeout() and returning 0 for 10 seconds.
	 As seen on perf sched:
   	 39243.913182 [0005]  mount.nfs[3794] 4607.938      0.017   9746.863
6. This continues until the 15s minor timeout condition is reached (in
   this case for 10 seconds). After which the ETIMEOUT is processed
   back to the caller, the cpu spinning stops, and normal operations
   continue

Fixes: 7de62bc09f ("SUNRPC dont update timeout value on connection reset")
Signed-off-by: Chris Dion <Christopher.Dion@dell.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2021-04-14 09:36:30 -04:00
Chuck Lever
6cf23783f7 SUNRPC: Remove trace_xprt_transmit_queued
This tracepoint can crash when dereferencing snd_task because
when some transports connect, they put a cookie in that field
instead of a pointer to an rpc_task.

BUG: KASAN: use-after-free in trace_event_raw_event_xprt_writelock_event+0x141/0x18e [sunrpc]
Read of size 2 at addr ffff8881a83bd3a0 by task git/331872

CPU: 11 PID: 331872 Comm: git Tainted: G S                5.12.0-rc2-00007-g3ab6e585a7f9 #1453
Hardware name: Supermicro SYS-6028R-T/X10DRi, BIOS 1.1a 10/16/2015
Call Trace:
 dump_stack+0x9c/0xcf
 print_address_description.constprop.0+0x18/0x239
 kasan_report+0x174/0x1b0
 trace_event_raw_event_xprt_writelock_event+0x141/0x18e [sunrpc]
 xprt_prepare_transmit+0x8e/0xc1 [sunrpc]
 call_transmit+0x4d/0xc6 [sunrpc]

Fixes: 9ce07ae5eb ("SUNRPC: Replace dprintk() call site in xprt_prepare_transmit")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2021-04-14 09:36:30 -04:00
Chuck Lever
e936a5970e SUNRPC: Add tracepoint that fires when an RPC is retransmitted
A separate tracepoint can be left enabled all the time to capture
rare but important retransmission events. So for example:

kworker/u26:3-568   [009]   156.967933: xprt_retransmit:      task:44093@5 xid=0xa25dbc79 nfsv3 WRITE ntrans=2

Or, for example, enable all nfs and nfs4 tracepoints, and set up a
trigger to disable tracing when xprt_retransmit fires to capture
everything that leads up to it.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2021-04-14 09:36:29 -04:00
Chuck Lever
7638e0bfae SUNRPC: Move fault injection call sites
I've hit some crashes that occur in the xprt_rdma_inject_disconnect
path. It appears that, for some provides, rdma_disconnect() can
take so long that the transport can disconnect and release its
hardware resources while rdma_disconnect() is still running,
resulting in a UAF in the provider.

The transport's fault injection method may depend on the stability
of transport data structures. That means it needs to be invoked
only from contexts that hold the transport write lock.

Fixes: 4a06825839 ("SUNRPC: Transport fault injection")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2021-04-14 09:36:29 -04:00
Trond Myklebust
d737e5d418 SUNRPC: Set TCP_CORK until the transmit queue is empty
When we have multiple RPC requests queued up, it makes sense to set the
TCP_CORK option while the transmit queue is non-empty.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2021-04-05 09:04:20 -04:00
Trond Myklebust
c87b056e58 SUNRPC: Remove unused function xprt_load_transport()
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-12-02 14:05:53 -05:00
Trond Myklebust
1fc5f13186 SUNRPC: Add a helper to return the transport identifier given a netid
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-12-02 14:05:52 -05:00
Trond Myklebust
9bccd26461 SUNRPC: Close a race with transport setup and module put
After we've looked up the transport module, we need to ensure it can't
go away until we've finished running the transport setup code.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-12-02 14:05:52 -05:00
Trond Myklebust
d5aa6b22e2 SUNRPC: xprt_load_transport() needs to support the netid "rdma6"
According to RFC5666, the correct netid for an IPv6 addressed RDMA
transport is "rdma6", which we've supported as a mount option since
Linux-4.7. The problem is when we try to load the module "xprtrdma6",
that will fail, since there is no modulealias of that name.

Fixes: 181342c5eb ("xprtrdma: Add rdma6 option to support NFS/RDMA IPv6")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-12-02 14:05:52 -05:00
Chuck Lever
6f9f17287e SUNRPC: Mitigate cond_resched() in xprt_transmit()
The original purpose of this expensive call is to prevent a long
queue of requests from blocking other work.

The cond_resched() call is unnecessary after just a single send
operation.

For longer queues, instead of invoking the kernel scheduler, simply
release the transport send lock and return to the RPC scheduler.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2020-09-21 10:21:09 -04:00
Chuck Lever
db0a86c426 SUNRPC: Replace connect dprintk call sites with a tracepoint
This trace event can be used to audit transport connections from the
client.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2020-09-21 10:21:09 -04:00
Chuck Lever
9ce07ae5eb SUNRPC: Replace dprintk() call site in xprt_prepare_transmit
Generate a trace event when an RPC request is queued without being
sent immediately.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2020-09-21 10:21:08 -04:00
Chuck Lever
09d2ba0cb1 SUNRPC: Update debugging instrumentation in xprt_do_reserve()
Replace a dprintk() with a tracepoint. The tracepoint marks the
point where an RPC request is assigned an XID.

Additional clean up: Remove trace_xprt_enq_xmit, which reports much
the same thing. That tracepoint was added for debugging commit
918f3c1fe8 ("SUNRPC: Improve latency for interactive tasks").

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2020-09-21 10:21:08 -04:00
Chuck Lever
7806948753 SUNRPC: Remove debugging instrumentation from xprt_release
These instruments don't appear to add any substantial value.

We already have this at the termination of each RPC:

          iozone-2617  [002]   975.713126: rpc_stats_latency:    task:418@5 xid=0x260eab5d nfsv3 LOOKUP backlog=15 rtt=32 execute=58
          iozone-2617  [002]   975.713127: xprt_release_cong:    task:418@5 snd_task:4294967295 cong=256 cwnd=16384
          iozone-2617  [002]   975.713127: xprt_put_cong:        task:418@5 snd_task:4294967295 cong=0 cwnd=16384

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2020-09-21 10:21:08 -04:00
Chuck Lever
e4378a0fdd SUNRPC: Remove trace_xprt_complete_rqst()
Request completion is already recorded by an "rpc_task_wakeup
queue=xprt_pending" trace record. A subsequent rpc_xdr_recvfrom
trace record shows the number of bytes received.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2020-09-21 10:21:08 -04:00
Gustavo A. R. Silva
df561f6688 treewide: Use fallthrough pseudo-keyword
Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
2020-08-23 17:36:59 -05:00