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authorAl Viro <viro@ftp.linux.org.uk>2006-10-08 09:32:15 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-10-08 15:32:35 -0400
commit7a39f52202a70ff6834e37053e2ee55c7d351621 (patch)
treede2f029495110336d2dd2b89205db2c62710dd50 /include/asm-sparc/spinlock.h
parent6d24c8dc2e656b02807aa0506405727d34c0376c (diff)
[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 'include/asm-sparc/spinlock.h')
-rw-r--r--include/asm-sparc/spinlock.h28
1 files changed, 27 insertions, 1 deletions
diff --git a/include/asm-sparc/spinlock.h b/include/asm-sparc/spinlock.h
index 557d08959d2f..de2249b267c6 100644
--- a/include/asm-sparc/spinlock.h
+++ b/include/asm-sparc/spinlock.h
@@ -129,6 +129,7 @@ static inline void __raw_write_lock(raw_rwlock_t *rw)
129 : /* no outputs */ 129 : /* no outputs */
130 : "r" (lp) 130 : "r" (lp)
131 : "g2", "g4", "memory", "cc"); 131 : "g2", "g4", "memory", "cc");
132 *(volatile __u32 *)&lp->lock = ~0U;
132} 133}
133 134
134static inline int __raw_write_trylock(raw_rwlock_t *rw) 135static inline int __raw_write_trylock(raw_rwlock_t *rw)
@@ -144,15 +145,40 @@ static inline int __raw_write_trylock(raw_rwlock_t *rw)
144 val = rw->lock & ~0xff; 145 val = rw->lock & ~0xff;
145 if (val) 146 if (val)
146 ((volatile u8*)&rw->lock)[3] = 0; 147 ((volatile u8*)&rw->lock)[3] = 0;
148 else
149 *(volatile u32*)&rw->lock = ~0U;
147 } 150 }
148 151
149 return (val == 0); 152 return (val == 0);
150} 153}
151 154
155static inline int __read_trylock(raw_rwlock_t *rw)
156{
157 register raw_rwlock_t *lp asm("g1");
158 register int res asm("o0");
159 lp = rw;
160 __asm__ __volatile__(
161 "mov %%o7, %%g4\n\t"
162 "call ___rw_read_try\n\t"
163 " ldstub [%%g1 + 3], %%g2\n"
164 : "=r" (res)
165 : "r" (lp)
166 : "g2", "g4", "memory", "cc");
167 return res;
168}
169
170#define __raw_read_trylock(lock) \
171({ unsigned long flags; \
172 int res; \
173 local_irq_save(flags); \
174 res = __read_trylock(lock); \
175 local_irq_restore(flags); \
176 res; \
177})
178
152#define __raw_write_unlock(rw) do { (rw)->lock = 0; } while(0) 179#define __raw_write_unlock(rw) do { (rw)->lock = 0; } while(0)
153 180
154#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock) 181#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
155#define __raw_read_trylock(lock) generic__raw_read_trylock(lock)
156 182
157#define _raw_spin_relax(lock) cpu_relax() 183#define _raw_spin_relax(lock) cpu_relax()
158#define _raw_read_relax(lock) cpu_relax() 184#define _raw_read_relax(lock) cpu_relax()