1346d00e1b
The HAVE_IRQ_EXIT_ON_IRQ_STACK option tells generic code that irq_exit()
is called while still running on the hard irq stack (hardirq_ctx[] in
the powerpc code).
Selecting the option means the generic code will *not* switch to the
softirq stack before running softirqs, because the code is already
running on the (mostly empty) hard irq stack.
But since commit 1b1b6a6f4cc0 ("powerpc: handle irq_enter/irq_exit in
interrupt handler wrappers"), irq_exit() is now called on the regular task
stack, not the hard irq stack.
That's because previously irq_exit() was called in __do_irq() which is
run on the hard irq stack, but now it is called in
interrupt_async_exit_prepare() which is called from do_irq() constructed
by the wrapper macro, which is after the switch back to the task stack.
So drop HAVE_IRQ_EXIT_ON_IRQ_STACK from the Kconfig. This will mean an
extra stack switch when processing some interrupts, but should
significantly reduce the likelihood of stack overflow.
It also means the softirq stack will be used for running softirqs from
other interrupts that don't use the hard irq stack, eg. timer interrupts.
Fixes: 1b1b6a6f4cc0 ("powerpc: handle irq_enter/irq_exit in interrupt handler wrappers")
Cc: stable@vger.kernel.org # v5.12+
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220525032639.1947280-1-mpe@ellerman.id.au
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.