I was having a little trouble with semaphores on my A5000. The code to decide
when to wake up other tasks appeared not to be doing the right thing, which
was causing processes to get stuck forever in __down_failed and similar places.
First I tried changing `orrls' to `orrle' in the implementation of up() which
seemed to improve things but not actually make everything work. I've appended
below the patch that I ended up using which seems to do the trick but isn't
very optimal.
Has anybody else seen this effect? The good news is that my A5k is now
working more reliably with a 2.2 kernel than ever before, including ELF shared
libraries. :-)
p.
--- include/asm-arm/proc-armo/semaphore.h Tue May 4 18:52:44 1999
+++ include/asm-arm/proc-armo/semaphore.h Sat May 15 15:28:44 1999
@@ -94,19 +94,16 @@
@ atomic up operation
mov r0, pc
orr lr, r0, #0x08000000
- and r0, r0, #0x0c000003
teqp lr, #0
ldr lr, [%0]
- adds lr, lr, #1
+ add lr, lr, #1
str lr, [%0]
- mov lr, pc, lsr #28
- orrls r0, r0, #0x80000000 @ set N
- teqp r0, lr, lsl #28
- movmi r0, %0
- blmi " SYMBOL_NAME_STR(__up_wakeup)
+ teqp r0, #0"
:
: "r" (sem)
- : "r0", "lr", "cc");
+ : "r0", "lr");
+ if (atomic_read(&sem->count) <= 0)
+ __up (sem);
}
#endif
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