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authorDavid Daney <ddaney@caviumnetworks.com>2009-03-27 10:07:02 -0700
committerRalf Baechle <ralf@linux-mips.org>2009-03-30 14:49:39 +0200
commit0e6826c73c9aa785ec58b52613df7699fb31af9a (patch)
treea85de8026984bbe94bf8ebc49873fcf0367782d9 /arch/mips
parentf5fd02a33e9a53480c7c489d3210b144d24da24e (diff)
downloadop-kernel-dev-0e6826c73c9aa785ec58b52613df7699fb31af9a.zip
op-kernel-dev-0e6826c73c9aa785ec58b52613df7699fb31af9a.tar.gz
MIPS: __raw_spin_lock() may spin forever on ticket wrap.
If the lock is not acquired and has to spin *and* the second attempt to acquire the lock fails, the delay time is not masked by the ticket range mask. If the ticket number wraps around to zero, the result is that the lock sampling delay is essentially infinite (due to casting -1 to an unsigned int). The fix: Always mask the difference between my_ticket and the current ticket value before calculating the delay. Signed-off-by: David Daney <ddaney@caviumnetworks.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips')
-rw-r--r--arch/mips/include/asm/spinlock.h8
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/mips/include/asm/spinlock.h b/arch/mips/include/asm/spinlock.h
index 0884947..10e8244 100644
--- a/arch/mips/include/asm/spinlock.h
+++ b/arch/mips/include/asm/spinlock.h
@@ -76,7 +76,7 @@ static inline void __raw_spin_lock(raw_spinlock_t *lock)
"2: \n"
" .subsection 2 \n"
"4: andi %[ticket], %[ticket], 0x1fff \n"
- "5: sll %[ticket], 5 \n"
+ " sll %[ticket], 5 \n"
" \n"
"6: bnez %[ticket], 6b \n"
" subu %[ticket], 1 \n"
@@ -85,7 +85,7 @@ static inline void __raw_spin_lock(raw_spinlock_t *lock)
" andi %[ticket], %[ticket], 0x1fff \n"
" beq %[ticket], %[my_ticket], 2b \n"
" subu %[ticket], %[my_ticket], %[ticket] \n"
- " b 5b \n"
+ " b 4b \n"
" subu %[ticket], %[ticket], 1 \n"
" .previous \n"
" .set pop \n"
@@ -113,7 +113,7 @@ static inline void __raw_spin_lock(raw_spinlock_t *lock)
" ll %[ticket], %[ticket_ptr] \n"
" \n"
"4: andi %[ticket], %[ticket], 0x1fff \n"
- "5: sll %[ticket], 5 \n"
+ " sll %[ticket], 5 \n"
" \n"
"6: bnez %[ticket], 6b \n"
" subu %[ticket], 1 \n"
@@ -122,7 +122,7 @@ static inline void __raw_spin_lock(raw_spinlock_t *lock)
" andi %[ticket], %[ticket], 0x1fff \n"
" beq %[ticket], %[my_ticket], 2b \n"
" subu %[ticket], %[my_ticket], %[ticket] \n"
- " b 5b \n"
+ " b 4b \n"
" subu %[ticket], %[ticket], 1 \n"
" .previous \n"
" .set pop \n"
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