linux.git/drivers/char/hw_random/core.c, branch v4.5 Linux kernel source tree hwrng: core - sleep interruptible in read 2015-12-04T14:21:45+00:00 Jiri Slaby jslaby@suse.cz 2015-11-27T15:50:43+00:00 1ab87298cb59b649d8d648d25dc15b36ab865f5a 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> 
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>
hwrng: core - Simplify RNG switching from sysfs 2015-09-21T14:00:41+00:00 Lee Jones lee.jones@linaro.org 2015-09-17T13:45:53+00:00 d9a53b01404fa602117220e98bb6c9b2b63f1e7f If we attempt to use sysfs to change the current RNG in the usual way i.e. issuing something like: `echo 8a8a000.rng > /sys/devices/virtual/misc/hw_random/rng_current` ... it will fail because the code doesn't currently take the '\n' into consideration. Well, now it does. Signed-off-by: Lee Jones <lee.jones@linaro.org> Acked-by: Peter Korsgaard <peter@korsgaard.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> 
If we attempt to use sysfs to change the current RNG in the usual
way i.e. issuing something like:

`echo 8a8a000.rng > /sys/devices/virtual/misc/hw_random/rng_current`

... it will fail because the code doesn't currently take the '\n'
into consideration.  Well, now it does.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
hwrng: core - correct error check of kthread_run call 2015-07-28T06:59:54+00:00 Martin Schwidefsky schwidefsky@de.ibm.com 2015-07-24T11:13:30+00:00 17fb874dee093139923af8ed36061faa92cc8e79 The kthread_run() function can return two different error values but the hwrng core only checks for -ENOMEM. If the other error value -EINTR is returned it is assigned to hwrng_fill and later used on a kthread_stop() call which naturally crashes. Cc: stable@vger.kernel.org Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> 
The kthread_run() function can return two different error values
but the hwrng core only checks for -ENOMEM. If the other error
value -EINTR is returned it is assigned to hwrng_fill and later
used on a kthread_stop() call which naturally crashes.

Cc: stable@vger.kernel.org
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Merge tag 'char-misc-4.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc 2015-04-21T16:42:58+00:00 Linus Torvalds torvalds@linux-foundation.org 2015-04-21T16:42:58+00:00 1fc149933fd49a5b0e7738dc0853dbfbac4ae0e1 Pull char/misc driver updates from Greg KH: "Here's the big char/misc driver patchset for 4.1-rc1. Lots of different driver subsystem updates here, nothing major, full details are in the shortlog. All of this has been in linux-next for a while" * tag 'char-misc-4.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (133 commits) mei: trace: remove unused TRACE_SYSTEM_STRING DTS: ARM: OMAP3-N900: Add lis3lv02d support Documentation: DT: lis302: update wakeup binding lis3lv02d: DT: add wakeup unit 2 and wakeup threshold lis3lv02d: DT: use s32 to support negative values Drivers: hv: hv_balloon: correctly handle num_pages>INT_MAX case Drivers: hv: hv_balloon: correctly handle val.freeram<num_pages case mei: replace check for connection instead of transitioning mei: use mei_cl_is_connected consistently mei: fix mei_poll operation hv_vmbus: Add gradually increased delay for retries in vmbus_post_msg() Drivers: hv: hv_balloon: survive ballooning request with num_pages=0 Drivers: hv: hv_balloon: eliminate jumps in piecewiese linear floor function Drivers: hv: hv_balloon: do not online pages in offline blocks hv: remove the per-channel workqueue hv: don't schedule new works in vmbus_onoffer()/vmbus_onoffer_rescind() hv: run non-blocking message handlers in the dispatch tasklet coresight: moving to new "hwtracing" directory coresight-tmc: Adding a status interface to sysfs coresight: remove the unnecessary configuration coresight-default-sink ... 
Pull char/misc driver updates from Greg KH:
 "Here's the big char/misc driver patchset for 4.1-rc1.

  Lots of different driver subsystem updates here, nothing major, full
  details are in the shortlog.

  All of this has been in linux-next for a while"

* tag 'char-misc-4.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (133 commits)
  mei: trace: remove unused TRACE_SYSTEM_STRING
  DTS: ARM: OMAP3-N900: Add lis3lv02d support
  Documentation: DT: lis302: update wakeup binding
  lis3lv02d: DT: add wakeup unit 2 and wakeup threshold
  lis3lv02d: DT: use s32 to support negative values
  Drivers: hv: hv_balloon: correctly handle num_pages>INT_MAX case
  Drivers: hv: hv_balloon: correctly handle val.freeram<num_pages case
  mei: replace check for connection instead of transitioning
  mei: use mei_cl_is_connected consistently
  mei: fix mei_poll operation
  hv_vmbus: Add gradually increased delay for retries in vmbus_post_msg()
  Drivers: hv: hv_balloon: survive ballooning request with num_pages=0
  Drivers: hv: hv_balloon: eliminate jumps in piecewiese linear floor function
  Drivers: hv: hv_balloon: do not online pages in offline blocks
  hv: remove the per-channel workqueue
  hv: don't schedule new works in vmbus_onoffer()/vmbus_onoffer_rescind()
  hv: run non-blocking message handlers in the dispatch tasklet
  coresight: moving to new "hwtracing" directory
  coresight-tmc: Adding a status interface to sysfs
  coresight: remove the unnecessary configuration coresight-default-sink
  ...
hwrng: Avoid manual device_create_file() calls 2015-03-25T10:44:53+00:00 Takashi Iwai tiwai@suse.de 2015-02-02T14:44:55+00:00 0daa7a0afd0fa7aad83cbde0fb341d7fbeac952c Use the new group field of struct miscdevice for managing the sysfs entries instead of manually adding/removing via device_create_file() and device_remove_file(). This simplifies the code a lot and fixes the possible races. Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Use the new group field of struct miscdevice for managing the sysfs
entries instead of manually adding/removing via device_create_file()
and device_remove_file().  This simplifies the code a lot and fixes
the possible races.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
hwrng: core - allow perfect entropy from hardware devices 2015-03-18T10:01:31+00:00 Keith Packard keithp@keithp.com 2015-03-18T07:17:00+00:00 506bf0c0464ace57169aadcf02ae397999c57bdd Hardware random number quality is measured from 0 (no entropy) to 1024 (perfect entropy). Allow hardware devices to assert the full range by truncating the device-provided value at 1024 instead of 1023. Signed-off-by: Keith Packard <keithp@keithp.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> 
Hardware random number quality is measured from 0 (no entropy) to 1024
(perfect entropy). Allow hardware devices to assert the full range by
truncating the device-provided value at 1024 instead of 1023.

Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
hwrng: add devm_* interfaces 2015-03-16T10:45:54+00:00 Dmitry Torokhov dmitry.torokhov@gmail.com 2015-03-12T21:00:02+00:00 4d9b519c9bcab5718053f8717dadad7b09b41f5e This change adds devm_hwrng_register and devm_hwrng_unregister which use can simplify error unwinding and unbinding code paths in device drivers. Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> 
This change adds devm_hwrng_register and devm_hwrng_unregister which
use can simplify error unwinding and unbinding code paths in device
drivers.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
hwrng: core - Move hwrng_init call into set_current_rng 2014-12-25T21:33:36+00:00 Herbert Xu herbert@gondor.apana.org.au 2014-12-23T05:40:22+00:00 90ac41bd40ad0571a10826eb26d53c84bd791f29 We always do hwrng_init in set_current_rng. In fact, our current reference count system relies on this. So make this explicit by moving hwrng_init into set_current_rng. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> 
We always do hwrng_init in set_current_rng.  In fact, our current
reference count system relies on this.  So make this explicit by
moving hwrng_init into set_current_rng.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
hwrng: core - Drop current rng in set_current_rng 2014-12-25T21:33:35+00:00 Herbert Xu herbert@gondor.apana.org.au 2014-12-23T05:40:21+00:00 ff77c150f71b761dcf29b9d1947df3165d2dc83e Rather than having callers of set_current_rng call drop_current_rng, we can do it directly in set_current_rng. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> 
Rather than having callers of set_current_rng call drop_current_rng,
we can do it directly in set_current_rng.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
hwrng: core - Do not register device opportunistically 2014-12-25T21:33:35+00:00 Herbert Xu herbert@gondor.apana.org.au 2014-12-23T05:40:19+00:00 ac3a497f13e42a99ed6fe188ebf2dcc39eb7ac20 Currently we only register the device when a valid RNG is added. However the way it's done is buggy because we test whether there is a current RNG to determine whether we need to register. As the current RNG may be missing due to a reinitialisation error this can lead to a reregistration of the device. As the device already has to handle a NULL current RNG anyway, let's just register the device always and remove the complexity. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> 
Currently we only register the device when a valid RNG is added.
However the way it's done is buggy because we test whether there
is a current RNG to determine whether we need to register.  As
the current RNG may be missing due to a reinitialisation error
this can lead to a reregistration of the device.

As the device already has to handle a NULL current RNG anyway,
let's just register the device always and remove the complexity.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>