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authorTejun Heo <tj@kernel.org>2013-05-01 02:27:22 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2013-05-01 04:04:02 +0400
commit3d1cb2059d9374e58da481b783332cf191cb6620 (patch)
treeb62afd1038ecabde21df35da3fbcc5e585b9516e /include/linux/workqueue.h
parentcd42d559e45e3563c74403e453f8954b593db69d (diff)
downloadlinux-3d1cb2059d9374e58da481b783332cf191cb6620.tar.xz
workqueue: include workqueue info when printing debug dump of a worker task
One of the problems that arise when converting dedicated custom threadpool to workqueue is that the shared worker pool used by workqueue anonimizes each worker making it more difficult to identify what the worker was doing on which target from the output of sysrq-t or debug dump from oops, BUG() and friends. This patch implements set_worker_desc() which can be called from any workqueue work function to set its description. When the worker task is dumped for whatever reason - sysrq-t, WARN, BUG, oops, lockdep assertion and so on - the description will be printed out together with the workqueue name and the worker function pointer. The printing side is implemented by print_worker_info() which is called from functions in task dump paths - sched_show_task() and dump_stack_print_info(). print_worker_info() can be safely called on any task in any state as long as the task struct itself is accessible. It uses probe_*() functions to access worker fields. It may print garbage if something went very wrong, but it wouldn't cause (another) oops. The description is currently limited to 24bytes including the terminating \0. worker->desc_valid and workder->desc[] are added and the 64 bytes marker which was already incorrect before adding the new fields is moved to the correct position. Here's an example dump with writeback updated to set the bdi name as worker desc. Hardware name: Bochs Modules linked in: Pid: 7, comm: kworker/u9:0 Not tainted 3.9.0-rc1-work+ #1 Workqueue: writeback bdi_writeback_workfn (flush-8:0) ffffffff820a3ab0 ffff88000f6e9cb8 ffffffff81c61845 ffff88000f6e9cf8 ffffffff8108f50f 0000000000000000 0000000000000000 ffff88000cde16b0 ffff88000cde1aa8 ffff88001ee19240 ffff88000f6e9fd8 ffff88000f6e9d08 Call Trace: [<ffffffff81c61845>] dump_stack+0x19/0x1b [<ffffffff8108f50f>] warn_slowpath_common+0x7f/0xc0 [<ffffffff8108f56a>] warn_slowpath_null+0x1a/0x20 [<ffffffff81200150>] bdi_writeback_workfn+0x2a0/0x3b0 ... Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Acked-by: Jan Kara <jack@suse.cz> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/workqueue.h')
-rw-r--r--include/linux/workqueue.h5
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 717975639378..623488fdc1f5 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -92,6 +92,9 @@ enum {
/* bit mask for work_busy() return values */
WORK_BUSY_PENDING = 1 << 0,
WORK_BUSY_RUNNING = 1 << 1,
+
+ /* maximum string length for set_worker_desc() */
+ WORKER_DESC_LEN = 24,
};
struct work_struct {
@@ -447,6 +450,8 @@ extern void workqueue_set_max_active(struct workqueue_struct *wq,
extern bool current_is_workqueue_rescuer(void);
extern bool workqueue_congested(int cpu, struct workqueue_struct *wq);
extern unsigned int work_busy(struct work_struct *work);
+extern __printf(1, 2) void set_worker_desc(const char *fmt, ...);
+extern void print_worker_info(const char *log_lvl, struct task_struct *task);
/**
* queue_work - queue work on a workqueue