Commit 0e6826c7 authored by David Daney's avatar David Daney Committed by Ralf Baechle

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: default avatarDavid Daney <ddaney@caviumnetworks.com>
Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent f5fd02a3
......@@ -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"
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment