X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=Documentation%2Flockdep-design.txt;h=938ea22f2cc096f6838a678217e463bf9ec0cd4d;hb=6d7003877c2f0578f1c08f66d05c3f72ef4ae596;hp=dab123db5a4fed62b324b9ffe2624fc04c0b5846;hpb=992caacf1141b31e94540eb31e0540e3da3a5e25;p=safe%2Fjmp%2Flinux-2.6 diff --git a/Documentation/lockdep-design.txt b/Documentation/lockdep-design.txt index dab123d..938ea22 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: [] mutex_lock+0x21/0x24 + (&sio_locks[i].lock){-.-...}, at: [] mutex_lock+0x21/0x24 but task is already holding lock: - (&sio_locks[i].lock){--..}, at: [] mutex_lock+0x21/0x24 + (&sio_locks[i].lock){-.-...}, at: [] 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 enabled + '.' acquired while irqs disabled '+' acquired in irq context - '-' acquired in process context with irqs disabled - '?' read-acquired both with irqs enabled and in irq context + '-' acquired with irqs enabled + '?' acquired in irq context with irqs enabled. Unused mutexes cannot be part of the cause of an error.