<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/arch/arm/kernel/smp.c, branch v7.0</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>Convert 'alloc_obj' family to use the new default GFP_KERNEL argument</title>
<updated>2026-02-22T01:09:51+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2026-02-22T00:37:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=bf4afc53b77aeaa48b5409da5c8da6bb4eff7f43'/>
<id>bf4afc53b77aeaa48b5409da5c8da6bb4eff7f43</id>
<content type='text'>
This was done entirely with mindless brute force, using

    git grep -l '\&lt;k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
        xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'

to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.

Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.

For the same reason the 'flex' versions will be done as a separate
conversion.

Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This was done entirely with mindless brute force, using

    git grep -l '\&lt;k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
        xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'

to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.

Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.

For the same reason the 'flex' versions will be done as a separate
conversion.

Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>treewide: Replace kmalloc with kmalloc_obj for non-scalar types</title>
<updated>2026-02-21T09:02:28+00:00</updated>
<author>
<name>Kees Cook</name>
<email>kees@kernel.org</email>
</author>
<published>2026-02-21T07:49:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=69050f8d6d075dc01af7a5f2f550a8067510366f'/>
<id>69050f8d6d075dc01af7a5f2f550a8067510366f</id>
<content type='text'>
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:

Single allocations:	kmalloc(sizeof(TYPE), ...)
are replaced with:	kmalloc_obj(TYPE, ...)

Array allocations:	kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with:	kmalloc_objs(TYPE, COUNT, ...)

Flex array allocations:	kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with:	kmalloc_flex(*PTR, FAM, COUNT, ...)

(where TYPE may also be *VAR)

The resulting allocations no longer return "void *", instead returning
"TYPE *".

Signed-off-by: Kees Cook &lt;kees@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:

Single allocations:	kmalloc(sizeof(TYPE), ...)
are replaced with:	kmalloc_obj(TYPE, ...)

Array allocations:	kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with:	kmalloc_objs(TYPE, COUNT, ...)

Flex array allocations:	kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with:	kmalloc_flex(*PTR, FAM, COUNT, ...)

(where TYPE may also be *VAR)

The resulting allocations no longer return "void *", instead returning
"TYPE *".

Signed-off-by: Kees Cook &lt;kees@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ARM: 9442/1: smp: Fix IPI alignment in /proc/interrupts</title>
<updated>2025-03-26T13:31:18+00:00</updated>
<author>
<name>Geert Uytterhoeven</name>
<email>geert+renesas@glider.be</email>
</author>
<published>2025-02-05T13:24:15+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=9cac324d6f4900f92d41db5fd6b73b6feb0bfb68'/>
<id>9cac324d6f4900f92d41db5fd6b73b6feb0bfb68</id>
<content type='text'>
On a system with less than 1000 interrupts, prec = 3, causing a
misalignment for the IPI interrupts.  E.g. on Koelsch (R-Car M2-W):

    200:          0          0  gpio-rcar   6 Edge      SW36
    IPI0:          0          0  CPU wakeup interrupts
    IPI1:          0          0  Timer broadcast interrupts
    IPI2:       1701       2844  Rescheduling interrupts
    IPI3:      10338      21181  Function call interrupts
    IPI4:          0          0  CPU stop interrupts
    IPI5:        651        825  IRQ work interrupts
    IPI6:          0          0  completion interrupts
    Err:          0

Fix this by adopting the same solution as used on arm64.

Signed-off-by: Geert Uytterhoeven &lt;geert+renesas@glider.be&gt;
Reviewed-by: Anshuman Khandual &lt;anshuman.khandual@arm.com&gt;
Signed-off-by: Russell King (Oracle) &lt;rmk+kernel@armlinux.org.uk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
On a system with less than 1000 interrupts, prec = 3, causing a
misalignment for the IPI interrupts.  E.g. on Koelsch (R-Car M2-W):

    200:          0          0  gpio-rcar   6 Edge      SW36
    IPI0:          0          0  CPU wakeup interrupts
    IPI1:          0          0  Timer broadcast interrupts
    IPI2:       1701       2844  Rescheduling interrupts
    IPI3:      10338      21181  Function call interrupts
    IPI4:          0          0  CPU stop interrupts
    IPI5:        651        825  IRQ work interrupts
    IPI6:          0          0  completion interrupts
    Err:          0

Fix this by adopting the same solution as used on arm64.

Signed-off-by: Geert Uytterhoeven &lt;geert+renesas@glider.be&gt;
Reviewed-by: Anshuman Khandual &lt;anshuman.khandual@arm.com&gt;
Signed-off-by: Russell King (Oracle) &lt;rmk+kernel@armlinux.org.uk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>nmi_backtrace: allow excluding an arbitrary CPU</title>
<updated>2023-08-18T17:19:00+00:00</updated>
<author>
<name>Douglas Anderson</name>
<email>dianders@chromium.org</email>
</author>
<published>2023-08-04T14:00:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=8d539b84f1e3478436f978ceaf55a0b6cab497b5'/>
<id>8d539b84f1e3478436f978ceaf55a0b6cab497b5</id>
<content type='text'>
The APIs that allow backtracing across CPUs have always had a way to
exclude the current CPU.  This convenience means callers didn't need to
find a place to allocate a CPU mask just to handle the common case.

Let's extend the API to take a CPU ID to exclude instead of just a
boolean.  This isn't any more complex for the API to handle and allows the
hardlockup detector to exclude a different CPU (the one it already did a
trace for) without needing to find space for a CPU mask.

Arguably, this new API also encourages safer behavior.  Specifically if
the caller wants to avoid tracing the current CPU (maybe because they
already traced the current CPU) this makes it more obvious to the caller
that they need to make sure that the current CPU ID can't change.

[akpm@linux-foundation.org: fix trigger_allbutcpu_cpu_backtrace() stub]
Link: https://lkml.kernel.org/r/20230804065935.v4.1.Ia35521b91fc781368945161d7b28538f9996c182@changeid
Signed-off-by: Douglas Anderson &lt;dianders@chromium.org&gt;
Acked-by: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: kernel test robot &lt;lkp@intel.com&gt;
Cc: Lecopzer Chen &lt;lecopzer.chen@mediatek.com&gt;
Cc: Petr Mladek &lt;pmladek@suse.com&gt;
Cc: Pingfan Liu &lt;kernelfans@gmail.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The APIs that allow backtracing across CPUs have always had a way to
exclude the current CPU.  This convenience means callers didn't need to
find a place to allocate a CPU mask just to handle the common case.

Let's extend the API to take a CPU ID to exclude instead of just a
boolean.  This isn't any more complex for the API to handle and allows the
hardlockup detector to exclude a different CPU (the one it already did a
trace for) without needing to find space for a CPU mask.

Arguably, this new API also encourages safer behavior.  Specifically if
the caller wants to avoid tracing the current CPU (maybe because they
already traced the current CPU) this makes it more obvious to the caller
that they need to make sure that the current CPU ID can't change.

[akpm@linux-foundation.org: fix trigger_allbutcpu_cpu_backtrace() stub]
Link: https://lkml.kernel.org/r/20230804065935.v4.1.Ia35521b91fc781368945161d7b28538f9996c182@changeid
Signed-off-by: Douglas Anderson &lt;dianders@chromium.org&gt;
Acked-by: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: kernel test robot &lt;lkp@intel.com&gt;
Cc: Lecopzer Chen &lt;lecopzer.chen@mediatek.com&gt;
Cc: Petr Mladek &lt;pmladek@suse.com&gt;
Cc: Pingfan Liu &lt;kernelfans@gmail.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ARM: smp: Switch to hotplug core state synchronization</title>
<updated>2023-05-15T11:44:57+00:00</updated>
<author>
<name>Thomas Gleixner</name>
<email>tglx@linutronix.de</email>
</author>
<published>2023-05-12T21:07:32+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=5490e769cdc7230cb93e804e656cce19d6c82253'/>
<id>5490e769cdc7230cb93e804e656cce19d6c82253</id>
<content type='text'>
Switch to the CPU hotplug core state tracking and synchronization
mechanim. No functional change intended.

Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Tested-by: Michael Kelley &lt;mikelley@microsoft.com&gt;
Tested-by: Oleksandr Natalenko &lt;oleksandr@natalenko.name&gt;
Tested-by: Helge Deller &lt;deller@gmx.de&gt; # parisc
Tested-by: Guilherme G. Piccoli &lt;gpiccoli@igalia.com&gt; # Steam Deck
Link: https://lore.kernel.org/r/20230512205256.635326070@linutronix.de
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Switch to the CPU hotplug core state tracking and synchronization
mechanim. No functional change intended.

Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Tested-by: Michael Kelley &lt;mikelley@microsoft.com&gt;
Tested-by: Oleksandr Natalenko &lt;oleksandr@natalenko.name&gt;
Tested-by: Helge Deller &lt;deller@gmx.de&gt; # parisc
Tested-by: Guilherme G. Piccoli &lt;gpiccoli@igalia.com&gt; # Steam Deck
Link: https://lore.kernel.org/r/20230512205256.635326070@linutronix.de
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'smp-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2023-04-28T22:03:43+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2023-04-28T22:03:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=f20730efbd305d42eded761f6fbd9a59d6125228'/>
<id>f20730efbd305d42eded761f6fbd9a59d6125228</id>
<content type='text'>
Pull SMP cross-CPU function-call updates from Ingo Molnar:

 - Remove diagnostics and adjust config for CSD lock diagnostics

 - Add a generic IPI-sending tracepoint, as currently there's no easy
   way to instrument IPI origins: it's arch dependent and for some major
   architectures it's not even consistently available.

* tag 'smp-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  trace,smp: Trace all smp_function_call*() invocations
  trace: Add trace_ipi_send_cpu()
  sched, smp: Trace smp callback causing an IPI
  smp: reword smp call IPI comment
  treewide: Trace IPIs sent via smp_send_reschedule()
  irq_work: Trace self-IPIs sent via arch_irq_work_raise()
  smp: Trace IPIs sent via arch_send_call_function_ipi_mask()
  sched, smp: Trace IPIs sent via send_call_function_single_ipi()
  trace: Add trace_ipi_send_cpumask()
  kernel/smp: Make csdlock_debug= resettable
  locking/csd_lock: Remove per-CPU data indirection from CSD lock debugging
  locking/csd_lock: Remove added data from CSD lock debugging
  locking/csd_lock: Add Kconfig option for csd_debug default
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull SMP cross-CPU function-call updates from Ingo Molnar:

 - Remove diagnostics and adjust config for CSD lock diagnostics

 - Add a generic IPI-sending tracepoint, as currently there's no easy
   way to instrument IPI origins: it's arch dependent and for some major
   architectures it's not even consistently available.

* tag 'smp-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  trace,smp: Trace all smp_function_call*() invocations
  trace: Add trace_ipi_send_cpu()
  sched, smp: Trace smp callback causing an IPI
  smp: reword smp call IPI comment
  treewide: Trace IPIs sent via smp_send_reschedule()
  irq_work: Trace self-IPIs sent via arch_irq_work_raise()
  smp: Trace IPIs sent via arch_send_call_function_ipi_mask()
  sched, smp: Trace IPIs sent via send_call_function_single_ipi()
  trace: Add trace_ipi_send_cpumask()
  kernel/smp: Make csdlock_debug= resettable
  locking/csd_lock: Remove per-CPU data indirection from CSD lock debugging
  locking/csd_lock: Remove added data from CSD lock debugging
  locking/csd_lock: Add Kconfig option for csd_debug default
</pre>
</div>
</content>
</entry>
<entry>
<title>cpu: Mark panic_smp_self_stop() __noreturn</title>
<updated>2023-04-14T15:31:25+00:00</updated>
<author>
<name>Josh Poimboeuf</name>
<email>jpoimboe@kernel.org</email>
</author>
<published>2023-04-12T23:49:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=7412a60decec2a6744cf773280ff17a0f89e8395'/>
<id>7412a60decec2a6744cf773280ff17a0f89e8395</id>
<content type='text'>
In preparation for improving objtool's handling of weak noreturn
functions, mark panic_smp_self_stop() __noreturn.

Signed-off-by: Josh Poimboeuf &lt;jpoimboe@kernel.org&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Link: https://lore.kernel.org/r/92d76ab5c8bf660f04fdcd3da1084519212de248.1681342859.git.jpoimboe@kernel.org
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In preparation for improving objtool's handling of weak noreturn
functions, mark panic_smp_self_stop() __noreturn.

Signed-off-by: Josh Poimboeuf &lt;jpoimboe@kernel.org&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Link: https://lore.kernel.org/r/92d76ab5c8bf660f04fdcd3da1084519212de248.1681342859.git.jpoimboe@kernel.org
</pre>
</div>
</content>
</entry>
<entry>
<title>treewide: Trace IPIs sent via smp_send_reschedule()</title>
<updated>2023-03-24T10:01:28+00:00</updated>
<author>
<name>Valentin Schneider</name>
<email>vschneid@redhat.com</email>
</author>
<published>2023-03-07T14:35:56+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=4c8c3c7f70a6779d30f5492acbc9978f4636fe7a'/>
<id>4c8c3c7f70a6779d30f5492acbc9978f4636fe7a</id>
<content type='text'>
To be able to trace invocations of smp_send_reschedule(), rename the
arch-specific definitions of it to arch_smp_send_reschedule() and wrap it
into an smp_send_reschedule() that contains a tracepoint.

Changes to include the declaration of the tracepoint were driven by the
following coccinelle script:

  @func_use@
  @@
  smp_send_reschedule(...);

  @include@
  @@
  #include &lt;trace/events/ipi.h&gt;

  @no_include depends on func_use &amp;&amp; !include@
  @@
    #include &lt;...&gt;
  +
  + #include &lt;trace/events/ipi.h&gt;

[csky bits]
[riscv bits]
Signed-off-by: Valentin Schneider &lt;vschneid@redhat.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Acked-by: Guo Ren &lt;guoren@kernel.org&gt;
Acked-by: Palmer Dabbelt &lt;palmer@rivosinc.com&gt;
Link: https://lore.kernel.org/r/20230307143558.294354-6-vschneid@redhat.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
To be able to trace invocations of smp_send_reschedule(), rename the
arch-specific definitions of it to arch_smp_send_reschedule() and wrap it
into an smp_send_reschedule() that contains a tracepoint.

Changes to include the declaration of the tracepoint were driven by the
following coccinelle script:

  @func_use@
  @@
  smp_send_reschedule(...);

  @include@
  @@
  #include &lt;trace/events/ipi.h&gt;

  @no_include depends on func_use &amp;&amp; !include@
  @@
    #include &lt;...&gt;
  +
  + #include &lt;trace/events/ipi.h&gt;

[csky bits]
[riscv bits]
Signed-off-by: Valentin Schneider &lt;vschneid@redhat.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Acked-by: Guo Ren &lt;guoren@kernel.org&gt;
Acked-by: Palmer Dabbelt &lt;palmer@rivosinc.com&gt;
Link: https://lore.kernel.org/r/20230307143558.294354-6-vschneid@redhat.com
</pre>
</div>
</content>
</entry>
<entry>
<title>sched, smp: Trace IPIs sent via send_call_function_single_ipi()</title>
<updated>2023-03-24T10:01:27+00:00</updated>
<author>
<name>Valentin Schneider</name>
<email>vschneid@redhat.com</email>
</author>
<published>2023-03-07T14:35:53+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=cc9cb0a71725aa8dd8d8f534a9b562bbf7981f75'/>
<id>cc9cb0a71725aa8dd8d8f534a9b562bbf7981f75</id>
<content type='text'>
send_call_function_single_ipi() is the thing that sends IPIs at the bottom
of smp_call_function*() via either generic_exec_single() or
smp_call_function_many_cond(). Give it an IPI-related tracepoint.

Note that this ends up tracing any IPI sent via __smp_call_single_queue(),
which covers __ttwu_queue_wakelist() and irq_work_queue_on() "for free".

Signed-off-by: Valentin Schneider &lt;vschneid@redhat.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Reviewed-by: Steven Rostedt (Google) &lt;rostedt@goodmis.org&gt;
Acked-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Link: https://lore.kernel.org/r/20230307143558.294354-3-vschneid@redhat.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
send_call_function_single_ipi() is the thing that sends IPIs at the bottom
of smp_call_function*() via either generic_exec_single() or
smp_call_function_many_cond(). Give it an IPI-related tracepoint.

Note that this ends up tracing any IPI sent via __smp_call_single_queue(),
which covers __ttwu_queue_wakelist() and irq_work_queue_on() "for free".

Signed-off-by: Valentin Schneider &lt;vschneid@redhat.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Reviewed-by: Steven Rostedt (Google) &lt;rostedt@goodmis.org&gt;
Acked-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Link: https://lore.kernel.org/r/20230307143558.294354-3-vschneid@redhat.com
</pre>
</div>
</content>
</entry>
<entry>
<title>sched/idle: Mark arch_cpu_idle_dead() __noreturn</title>
<updated>2023-03-08T16:44:28+00:00</updated>
<author>
<name>Josh Poimboeuf</name>
<email>jpoimboe@kernel.org</email>
</author>
<published>2023-02-14T07:05:58+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=071c44e4278156f18a6a56958617223b6bffa6ab'/>
<id>071c44e4278156f18a6a56958617223b6bffa6ab</id>
<content type='text'>
Before commit 076cbf5d2163 ("x86/xen: don't let xen_pv_play_dead()
return"), in Xen, when a previously offlined CPU was brought back
online, it unexpectedly resumed execution where it left off in the
middle of the idle loop.

There were some hacks to make that work, but the behavior was surprising
as do_idle() doesn't expect an offlined CPU to return from the dead (in
arch_cpu_idle_dead()).

Now that Xen has been fixed, and the arch-specific implementations of
arch_cpu_idle_dead() also don't return, give it a __noreturn attribute.

This will cause the compiler to complain if an arch-specific
implementation might return.  It also improves code generation for both
caller and callee.

Also fixes the following warning:

  vmlinux.o: warning: objtool: do_idle+0x25f: unreachable instruction

Reported-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Tested-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Link: https://lore.kernel.org/r/60d527353da8c99d4cf13b6473131d46719ed16d.1676358308.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf &lt;jpoimboe@kernel.org&gt;
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<pre>
Before commit 076cbf5d2163 ("x86/xen: don't let xen_pv_play_dead()
return"), in Xen, when a previously offlined CPU was brought back
online, it unexpectedly resumed execution where it left off in the
middle of the idle loop.

There were some hacks to make that work, but the behavior was surprising
as do_idle() doesn't expect an offlined CPU to return from the dead (in
arch_cpu_idle_dead()).

Now that Xen has been fixed, and the arch-specific implementations of
arch_cpu_idle_dead() also don't return, give it a __noreturn attribute.

This will cause the compiler to complain if an arch-specific
implementation might return.  It also improves code generation for both
caller and callee.

Also fixes the following warning:

  vmlinux.o: warning: objtool: do_idle+0x25f: unreachable instruction

Reported-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Tested-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Link: https://lore.kernel.org/r/60d527353da8c99d4cf13b6473131d46719ed16d.1676358308.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf &lt;jpoimboe@kernel.org&gt;
</pre>
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</content>
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