]> git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/commit
hwrng: core - sleep interruptible in read
authorJiri Slaby <jslaby@suse.cz>
Fri, 27 Nov 2015 15:50:43 +0000 (16:50 +0100)
committerHerbert Xu <herbert@gondor.apana.org.au>
Fri, 4 Dec 2015 14:21:45 +0000 (22:21 +0800)
commit1ab87298cb59b649d8d648d25dc15b36ab865f5a
tree8374d05359f2957f211c508ba27aac5272d87db8
parentc012a79d0ce95bd8488a5a44cd8c00c275774518
hwrng: core - sleep interruptible in read

hwrng kthread can be waiting via hwrng_fillfn for some data from a rng
like virtio-rng:
hwrng           D ffff880093e17798     0   382      2 0x00000000
...
Call Trace:
 [<ffffffff817339c6>] wait_for_completion_killable+0x96/0x210
 [<ffffffffa00aa1b7>] virtio_read+0x57/0xf0 [virtio_rng]
 [<ffffffff814f4a35>] hwrng_fillfn+0x75/0x130
 [<ffffffff810aa243>] kthread+0xf3/0x110

And when some user program tries to read the /dev node in this state,
we get:
rngd            D ffff880093e17798     0   762      1 0x00000004
...
Call Trace:
 [<ffffffff817351ac>] mutex_lock_nested+0x15c/0x3e0
 [<ffffffff814f478e>] rng_dev_read+0x6e/0x240
 [<ffffffff81231958>] __vfs_read+0x28/0xe0
 [<ffffffff81232393>] vfs_read+0x83/0x130

And this is indeed unkillable. So use mutex_lock_interruptible
instead of mutex_lock in rng_dev_read and exit immediatelly when
interrupted. And possibly return already read data, if any (as POSIX
allows).

v2: use ERESTARTSYS instead of EINTR

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: <linux-crypto@vger.kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
drivers/char/hw_random/core.c