Clear the exclusive monitor when returning from an exception

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The patch adds a CLREX or dummy STREX to the exception return path. This
is needed because several atomic/locking operations use a pair of
LDREX/STREXEQ and the EQ condition may not always be satisfied. This
would leave the exclusive monitor status set and may cause problems with
atomic/locking operations in the interrupted code.

With this patch, the atomic_set() operation can be a simple STR
instruction (on SMP systems, the global exclusive monitor is cleared by
STR anyway). Clearing the exclusive monitor during context switch is no
longer needed as this is handled by the exception return path anyway.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Jamie Lokier <jamie@shareable.org>

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This commit is contained in:

Catalin Marinas 2009-09-18 23:27:05 +01:00

parent df58bee21e

commit 200b812d00

3 changed files with 21 additions and 26 deletions

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26

arch/arm/include/asm/atomic.h

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7

arch/arm/kernel/entry-armv.S

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14

arch/arm/kernel/entry-header.S

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