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| author | Al Viro <viro@ftp.linux.org.uk> | 2006-10-08 17:32:15 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-10-08 23:32:35 +0400 |
| commit | 7a39f52202a70ff6834e37053e2ee55c7d351621 (patch) | |
| tree | de2f029495110336d2dd2b89205db2c62710dd50 /arch/sparc/lib/locks.S | |
| parent | 6d24c8dc2e656b02807aa0506405727d34c0376c (diff) | |
| download | linux-7a39f52202a70ff6834e37053e2ee55c7d351621.tar.xz | |
[PATCH] sparc32 rwlock fix
read_trylock() is broken on sparc32 (doesn't build and didn't work
right, actually). Proposed fix:
- make "writer holds lock" distinguishable from "reader tries to grab
lock"
- have __raw_read_trylock() try to acquire the mutex (in LSB of lock),
terminating spin if we see that there's writer holding it. Then do
the rest as we do in read_lock().
Thanks to Ingo for discussion...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/sparc/lib/locks.S')
| -rw-r--r-- | arch/sparc/lib/locks.S | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/arch/sparc/lib/locks.S b/arch/sparc/lib/locks.S index 95fa48424967..b1df55cb2215 100644 --- a/arch/sparc/lib/locks.S +++ b/arch/sparc/lib/locks.S @@ -25,6 +25,15 @@ ___rw_read_enter_spin_on_wlock: ldstub [%g1 + 3], %g2 b ___rw_read_enter_spin_on_wlock ldub [%g1 + 3], %g2 +___rw_read_try_spin_on_wlock: + andcc %g2, 0xff, %g0 + be,a ___rw_read_try + ldstub [%g1 + 3], %g2 + xnorcc %g2, 0x0, %o0 /* if g2 is ~0, set o0 to 0 and bugger off */ + bne,a ___rw_read_enter_spin_on_wlock + ld [%g1], %g2 + retl + mov %g4, %o7 ___rw_read_exit_spin_on_wlock: orcc %g2, 0x0, %g0 be,a ___rw_read_exit @@ -60,6 +69,17 @@ ___rw_read_exit: retl mov %g4, %o7 + .globl ___rw_read_try +___rw_read_try: + orcc %g2, 0x0, %g0 + bne ___rw_read_try_spin_on_wlock + ld [%g1], %g2 + add %g2, 1, %g2 + st %g2, [%g1] + set 1, %o1 + retl + mov %g4, %o7 + .globl ___rw_write_enter ___rw_write_enter: orcc %g2, 0x0, %g0 |