From: "Paul E. McKenney" <paulmck@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: kernel-team@fb.com, tglx@linutronix.de,
gregkh@linuxfoundation.org, rmk+kernel@armlinux.org.uk,
nico@fluxnic.net
Subject: [PATCH UP] Make smp_call_function_single() match SMP semantics
Date: Wed, 5 Feb 2020 06:34:09 -0800 [thread overview]
Message-ID: <20200205143409.GA7021@paulmck-ThinkPad-P72> (raw)
In CONFIG_SMP=y kernels, smp_call_function_single() returns -ENXIO when
invoked for a non-existent CPU. In contrast, in CONFIG_SMP=n kernels,
a splat is emitted and smp_call_function_single() otherwise silently
ignores its "cpu" argument, instead pretending that the caller intended
to have something happen on CPU 0. Given that there is now code that
expects smp_call_function_single() to return an error if a bad CPU was
specified, this difference in semantics needs to be addressed.
This commit therefore brings the semantics of the CONFIG_SMP=n version
of smp_call_function_single() into alignment with its CONFIG_SMP=y
counterpart.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
up.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/up.c b/kernel/up.c
index 862b460..a504e81 100644
--- a/kernel/up.c
+++ b/kernel/up.c
@@ -14,7 +14,8 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
{
unsigned long flags;
- WARN_ON(cpu != 0);
+ if (cpu != 0)
+ return -ENXIO;
local_irq_save(flags);
func(info);
next reply other threads:[~2020-02-05 14:34 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-05 14:34 Paul E. McKenney [this message]
2020-02-07 14:37 ` [tip: smp/urgent] smp/up: Make smp_call_function_single() match SMP semantics tip-bot2 for Paul E. McKenney
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