Commit Graph

10 Commits

Author SHA1 Message Date
Thomas Gleixner
ddb6c9b58a locking, rwsem: Annotate inner lock as raw
There is no reason to allow the lock protecting rwsems (the
ownerless variant) to be preemptible on -rt. Convert it to raw.

In mainline this change documents the low level nature of
the lock - otherwise there's no functional difference. Lockdep
and Sparse checking will work as usual.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-09-13 11:11:59 +02:00
Kevin Hilman
3eac4abaa6 rwsem generic spinlock: use IRQ save/restore spinlocks
rwsems can be used with IRQs disabled, particularily in early boot
before IRQs are enabled.  Currently the spin_unlock_irq() usage in the
slow-patch will unconditionally enable interrupts and cause problems
since interrupts are not yet initialized or enabled.

This patch uses save/restore versions of IRQ spinlocks in the slowpath
to ensure interrupts are not unintentionally disabled.

Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-04-07 16:15:05 -07:00
Amerigo Wang
29671f22a8 rwsem: fix rwsem_is_locked() bugs
rwsem_is_locked() tests ->activity without locks, so we should always keep
->activity consistent.  However, the code in __rwsem_do_wake() breaks this
rule, it updates ->activity after _all_ readers waken up, this may give
some reader a wrong ->activity value, thus cause rwsem_is_locked() behaves
wrong.

Quote from Andrew:

"
- we have one or more processes sleeping in down_read(), waiting for access.

- we wake one or more processes up without altering ->activity

- they start to run and they do rwsem_is_locked().  This incorrectly
  returns "false", because the waker process is still crunching away in
  __rwsem_do_wake().

- the waker now alters ->activity, but it was too late.
"

So we need get a spinlock to protect this.  And rwsem_is_locked() should
not block, thus we use spin_trylock_irqsave().

[akpm@linux-foundation.org: simplify code]
Reported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Cc: Ben Woodard <bwoodard@llnl.gov>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: WANG Cong <amwang@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 08:53:26 -08:00
Amerigo Wang
118d52da18 rwsem-spinlock: remove useless function exports
These functions need not to be exported, since no drivers should use them.

__init_rwsem() is an exception, because init_rwsem(), which is a macro,
is used.

Signed-off-by: WANG Cong <amwang@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 08:53:26 -08:00
Harvey Harrison
9f741cb8fe lib: remove fastcall from lib/*
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-08 09:22:31 -08:00
Peter Zijlstra
4dfbb9d8c6 Lockdep: add lockdep_set_class_and_subclass() and lockdep_set_subclass()
This annotation makes it possible to assign a subclass on lock init. This
annotation is meant to reduce the _nested() annotations by assigning a
default subclass.

One could do without this annotation and rely on lockdep_set_class()
exclusively, but that would require a manual stack of struct lock_class_key
objects.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
2006-10-11 01:45:14 -04:00
Ingo Molnar
4ea2176dfa [PATCH] lockdep: prove rwsem locking correctness
Use the lock validator framework to prove rwsem locking correctness.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-03 15:27:04 -07:00
Ingo Molnar
c4e05116a2 [PATCH] lockdep: clean up rwsems
Clean up rwsems.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-03 15:27:01 -07:00
akpm@osdl.org
d59dd4620f [PATCH] use smp_mb/wmb/rmb where possible
Replace a number of memory barriers with smp_ variants.  This means we won't
take the unnecessary hit on UP machines.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-05-01 08:58:47 -07:00
Linus Torvalds
1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00