kmod: handle UMH_WAIT_PROC from system unbound workqueue
authorFrederic Weisbecker <fweisbec@gmail.com>
Wed, 9 Sep 2015 22:38:25 +0000 (15:38 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 10 Sep 2015 20:29:01 +0000 (13:29 -0700)
commitbb304a5c6fc63d8506cd9741a3a5f35b73605625
tree39d30e22c712abfaa9d4c2912fafb2a7ae6ad8c6
parent90f023030e26ce8f981b3e688cb79329d8d07cc3
kmod: handle UMH_WAIT_PROC from system unbound workqueue

The UMH_WAIT_PROC handler runs in its own thread in order to make sure
that waiting for the exec kernel thread completion won't block other
usermodehelper queued jobs.

On older workqueue implementations, worklets couldn't sleep without
blocking the rest of the queue.  But now the workqueue subsystem handles
that.  Khelper still had the older limitation due to its singlethread
properties but we replaced it to system unbound workqueues.

Those are affine to the current node and can block up to some number of
instances.

They are a good candidate to handle UMH_WAIT_PROC assuming that we have
enough system unbound workers to handle lots of parallel usermodehelper
jobs.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/kmod.c