From 0e6826c73c9aa785ec58b52613df7699fb31af9a Mon Sep 17 00:00:00 2001 From: David Daney Date: Fri, 27 Mar 2009 10:07:02 -0700 Subject: [PATCH] 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 Signed-off-by: Ralf Baechle --- arch/mips/include/asm/spinlock.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/mips/include/asm/spinlock.h b/arch/mips/include/asm/spinlock.h index 0884947ebe27..10e82441b496 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" -- 2.34.1