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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2009-01-22 17:53:47 +0100
committerIngo Molnar <mingo@elte.hu>2009-02-14 23:28:22 +0100
commitf510b233cfc7bfd57b6007071c52aa42e3d16b06 (patch)
treed7e91f4d82ee3bed078f5813377b73a1eb7e382f /Documentation/lockdep-design.txt
parent3ff176ca47911630d1555f150d36daa2d0819ea9 (diff)
downloadvexpress-lsk-f510b233cfc7bfd57b6007071c52aa42e3d16b06.tar.gz
lockdep: get_user_chars() redo
Generic, states independent, get_user_chars(). Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'Documentation/lockdep-design.txt')
-rw-r--r--Documentation/lockdep-design.txt30
1 files changed, 17 insertions, 13 deletions
diff --git a/Documentation/lockdep-design.txt b/Documentation/lockdep-design.txt
index 48877301815..938ea22f2cc 100644
--- a/Documentation/lockdep-design.txt
+++ b/Documentation/lockdep-design.txt
@@ -27,33 +27,37 @@ lock-class.
State
-----
-The validator tracks lock-class usage history into 5 separate state bits:
+The validator tracks lock-class usage history into 4n + 1 separate state bits:
-- 'ever held in hardirq context' [ == hardirq-safe ]
-- 'ever held in softirq context' [ == softirq-safe ]
-- 'ever held with hardirqs enabled' [ == hardirq-unsafe ]
-- 'ever held with softirqs and hardirqs enabled' [ == softirq-unsafe ]
+- 'ever held in STATE context'
+- 'ever head as readlock in STATE context'
+- 'ever head with STATE enabled'
+- 'ever head as readlock with STATE enabled'
+
+Where STATE can be either one of (kernel/lockdep_states.h)
+ - hardirq
+ - softirq
+ - reclaim_fs
- 'ever used' [ == !unused ]
-When locking rules are violated, these 4 state bits are presented in the
-locking error messages, inside curlies. A contrived example:
+When locking rules are violated, these state bits are presented in the
+locking error messages, inside curlies. A contrived example:
modprobe/2287 is trying to acquire lock:
- (&sio_locks[i].lock){--..}, at: [<c02867fd>] mutex_lock+0x21/0x24
+ (&sio_locks[i].lock){-.-...}, at: [<c02867fd>] mutex_lock+0x21/0x24
but task is already holding lock:
- (&sio_locks[i].lock){--..}, at: [<c02867fd>] mutex_lock+0x21/0x24
+ (&sio_locks[i].lock){-.-...}, at: [<c02867fd>] mutex_lock+0x21/0x24
-The bit position indicates hardirq, softirq, hardirq-read,
-softirq-read respectively, and the character displayed in each
-indicates:
+The bit position indicates STATE, STATE-read, for each of the states listed
+above, and the character displayed in each indicates:
'.' acquired while irqs disabled
'+' acquired in irq context
'-' acquired with irqs enabled
- '?' read acquired in irq context with irqs enabled.
+ '?' acquired in irq context with irqs enabled.
Unused mutexes cannot be part of the cause of an error.