linux.git/include/asm-mips/spinlock.h, branch master

MIPS: Move headfiles to new location below arch/mips/include

2008-10-11T15:18:52+00:00

Signed-off-by: Ralf Baechle

[MIPS] Make support for weakly ordered LL/SC a config option.

2007-07-20T17:57:39+00:00

None of weakly ordered processor supported in tree need this but it seems
like this could change ...

Signed-off-by: Ralf Baechle

[MIPS] Fix __raw_read_trylock() to allow multiple readers

2007-03-07T00:07:17+00:00

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 
Signed-off-by: Ralf Baechle

[MIPS] Improve branch prediction in ll/sc atomic operations.

2007-02-13T22:40:50+00:00

Now that finally all supported versions of binutils have functioning
support for .subsection use .subsection to tweak the branch prediction

I did not modify the R10000 errata variants because it seems unclear if
this will invalidate the workaround which actually relies on the cheesy
prediction of branch likely to cause a misspredict if the sc was
successful.

Signed-off-by: Ralf Baechle

[MIPS] Cleanup memory barriers for weakly ordered systems.

2006-12-04T22:43:14+00:00

Also the R4000 / R4600 LL/SC instructions imply a sync so no explicit sync
needed.

Signed-off-by: Ralf Baechle

[PATCH] Directed yield: cpu_relax variants for spinlocks and rw-locks

2006-10-01T07:39:21+00:00

On systems running with virtual cpus there is optimization potential in
regard to spinlocks and rw-locks.  If the virtual cpu that has taken a lock
is known to a cpu that wants to acquire the same lock it is beneficial to
yield the timeslice of the virtual cpu in favour of the cpu that has the
lock (directed yield).

With CONFIG_PREEMPT="n" this can be implemented by the architecture without
common code changes.  Powerpc already does this.

With CONFIG_PREEMPT="y" the lock loops are coded with _raw_spin_trylock,
_raw_read_trylock and _raw_write_trylock in kernel/spinlock.c.  If the lock
could not be taken cpu_relax is called.  A directed yield is not possible
because cpu_relax doesn't know anything about the lock.  To be able to
yield the lock in favour of the current lock holder variants of cpu_relax
for spinlocks and rw-locks are needed.  The new _raw_spin_relax,
_raw_read_relax and _raw_write_relax primitives differ from cpu_relax
insofar that they have an argument: a pointer to the lock structure.

Signed-off-by: Martin Schwidefsky 
Cc: Ingo Molnar 
Cc: Paul Mackerras 
Cc: Haavard Skinnemoen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[MIPS] Replace generic__raw_read_trylock usage

2006-09-27T12:37:39+00:00

generic__raw_read_trylock() is a defect generic function actually doing
a __raw_read_lock ...

Signed-off-by: Ralf Baechle

More configcheck fixes.

2005-10-29T18:32:40+00:00

Signed-off-by: Ralf Baechle

Move sync into the delay slot here also.

2005-10-29T18:31:08+00:00

Signed-off-by: Ralf Baechle

Define __raw_read_can_lock / __raw_write_can_lock.

2005-10-29T18:30:22+00:00

Signed-off-by: Ralf Baechle