[MIPS] Fix __raw_read_trylock() to allow multiple readers
authorDave Johnson <djohnson+linux-mips@sw.starentnetworks.com>
Tue, 6 Mar 2007 01:50:27 +0000 (20:50 -0500)
committerRalf Baechle <ralf@linux-mips.org>
Wed, 7 Mar 2007 00:07:17 +0000 (00:07 +0000)
A deadlock can occur for mixed irq and non-irq rwlock readers if a 2nd
reader attempts to take lock by looping around __raw_read_trylock().

Signed-off-by: Dave Johnson <djohnson+linux-mips@sw.starentnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
include/asm-mips/spinlock.h

index f1755d28a36a6f3a44f44bebd3f2f061617e8695..35e431cd796bf499bccfc2d6ef4bd76ad578009e 100644 (file)
@@ -287,7 +287,7 @@ static inline int __raw_read_trylock(raw_rwlock_t *rw)
                "       .set    noreorder       # __raw_read_trylock    \n"
                "       li      %2, 0                                   \n"
                "1:     ll      %1, %3                                  \n"
-               "       bnez    %1, 2f                                  \n"
+               "       bltz    %1, 2f                                  \n"
                "        addu   %1, 1                                   \n"
                "       sc      %1, %0                                  \n"
                "       .set    reorder                                 \n"
@@ -304,7 +304,7 @@ static inline int __raw_read_trylock(raw_rwlock_t *rw)
                "       .set    noreorder       # __raw_read_trylock    \n"
                "       li      %2, 0                                   \n"
                "1:     ll      %1, %3                                  \n"
-               "       bnez    %1, 2f                                  \n"
+               "       bltz    %1, 2f                                  \n"
                "        addu   %1, 1                                   \n"
                "       sc      %1, %0                                  \n"
                "       beqz    %1, 1b                                  \n"