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authorJiri Slaby <jslaby@suse.cz>2015-11-27 18:50:43 +0300
committerHerbert Xu <herbert@gondor.apana.org.au>2015-12-04 17:21:45 +0300
commit1ab87298cb59b649d8d648d25dc15b36ab865f5a (patch)
tree8374d05359f2957f211c508ba27aac5272d87db8 /drivers/char
parentc012a79d0ce95bd8488a5a44cd8c00c275774518 (diff)
downloadlinux-1ab87298cb59b649d8d648d25dc15b36ab865f5a.tar.xz
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>
Diffstat (limited to 'drivers/char')
-rw-r--r--drivers/char/hw_random/core.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index 6f497aa1b276..9203f2d130c0 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -238,7 +238,10 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf,
goto out;
}
- mutex_lock(&reading_mutex);
+ if (mutex_lock_interruptible(&reading_mutex)) {
+ err = -ERESTARTSYS;
+ goto out_put;
+ }
if (!data_avail) {
bytes_read = rng_get_data(rng, rng_buffer,
rng_buffer_size(),
@@ -288,6 +291,7 @@ out:
out_unlock_reading:
mutex_unlock(&reading_mutex);
+out_put:
put_rng(rng);
goto out;
}