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authorLinus Torvalds <torvalds@linux-foundation.org>2009-08-21 09:23:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-08-21 09:23:57 -0700
commit83d349f35e1ae72268c5104dbf9ab2ae635425d4 (patch)
tree329927ef85bd5b508434421cd275bdf67a4cca98
parent429966b8f644dda2afddb4f834a944e9b46a7645 (diff)
x86: don't send an IPI to the empty set of CPU's
The default_send_IPI_mask_logical() function uses the "flat" APIC mode to send an IPI to a set of CPU's at once, but if that set happens to be empty, some older local APIC's will apparently be rather unhappy. So just warn if a caller gives us an empty mask, and ignore it. This fixes a regression in 2.6.30.x, due to commit 4595f9620 ("x86: change flush_tlb_others to take a const struct cpumask"), documented here: http://bugzilla.kernel.org/show_bug.cgi?id=13933 which causes a silent lock-up. It only seems to happen on PPro, P2, P3 and Athlon XP cores. Most developers sadly (or not so sadly, if you're a developer..) have more modern CPU's. Also, on x86-64 we don't use the flat APIC mode, so it would never trigger there even if the APIC didn't like sending an empty IPI mask. Reported-by: Pavel Vilim <wylda@volny.cz> Reported-and-tested-by: Thomas Björnell <thomas.bjornell@gmail.com> Reported-and-tested-by: Martin Rogge <marogge@onlinehome.de> Cc: Mike Travis <travis@sgi.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--arch/x86/kernel/apic/ipi.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/kernel/apic/ipi.c b/arch/x86/kernel/apic/ipi.c
index dbf5445727a9..6ef00ba4c886 100644
--- a/arch/x86/kernel/apic/ipi.c
+++ b/arch/x86/kernel/apic/ipi.c
@@ -106,6 +106,9 @@ void default_send_IPI_mask_logical(const struct cpumask *cpumask, int vector)
unsigned long mask = cpumask_bits(cpumask)[0];
unsigned long flags;
+ if (WARN_ONCE(!mask, "empty IPI mask"))
+ return;
+
local_irq_save(flags);
WARN_ON(mask & ~cpumask_bits(cpu_online_mask)[0]);
__default_send_IPI_dest_field(mask, vector, apic->dest_logical);