On Fri, Nov 27, 2015 at 04:50:43PM +0100, Jiri Slaby wrote: > 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@xxxxxxx> > Cc: Matt Mackall <mpm@xxxxxxxxxxx> > Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> > Cc: <linux-crypto@xxxxxxxxxxxxxxx> Patch applied. Thanks. -- Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
