diff options
| author | Stephen Boyd <swboyd@chromium.org> | 2019-09-05 09:41:12 -0700 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2019-09-09 23:48:41 +1000 |
| commit | 59b569480dc8bb9dce57cdff133853a842dfd805 (patch) | |
| tree | 189247a11645363b681fd7b7578121bcc6fc5e7b /drivers/char | |
| parent | 347bce3eab76b2e07147f8d4b4436d59264f8132 (diff) | |
random: Use wait_event_freezable() in add_hwgenerator_randomness()
Sebastian reports that after commit ff296293b353 ("random: Support freezable
kthreads in add_hwgenerator_randomness()") we can call might_sleep() when the
task state is TASK_INTERRUPTIBLE (state=1). This leads to the following warning.
do not call blocking ops when !TASK_RUNNING; state=1 set at [<00000000349d1489>] prepare_to_wait_event+0x5a/0x180
WARNING: CPU: 0 PID: 828 at kernel/sched/core.c:6741 __might_sleep+0x6f/0x80
Modules linked in:
CPU: 0 PID: 828 Comm: hwrng Not tainted 5.3.0-rc7-next-20190903+ #46
RIP: 0010:__might_sleep+0x6f/0x80
Call Trace:
kthread_freezable_should_stop+0x1b/0x60
add_hwgenerator_randomness+0xdd/0x130
hwrng_fillfn+0xbf/0x120
kthread+0x10c/0x140
ret_from_fork+0x27/0x50
We shouldn't call kthread_freezable_should_stop() from deep within the
wait_event code because the task state is still set as
TASK_INTERRUPTIBLE instead of TASK_RUNNING and
kthread_freezable_should_stop() will try to call into the freezer with
the task in the wrong state. Use wait_event_freezable() instead so that
it calls schedule() in the right place and tries to enter the freezer
when the task state is TASK_RUNNING instead.
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Keerthy <j-keerthy@ti.com>
Fixes: ff296293b353 ("random: Support freezable kthreads in add_hwgenerator_randomness()")
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'drivers/char')
| -rw-r--r-- | drivers/char/random.c | 12 |
1 files changed, 5 insertions, 7 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c index e2e85ca16410..5b799aa973a3 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -327,6 +327,7 @@ #include <linux/percpu.h> #include <linux/cryptohash.h> #include <linux/fips.h> +#include <linux/freezer.h> #include <linux/ptrace.h> #include <linux/workqueue.h> #include <linux/irq.h> @@ -2429,7 +2430,6 @@ void add_hwgenerator_randomness(const char *buffer, size_t count, size_t entropy) { struct entropy_store *poolp = &input_pool; - bool frozen = false; if (unlikely(crng_init == 0)) { crng_fast_load(buffer, count); @@ -2440,12 +2440,10 @@ void add_hwgenerator_randomness(const char *buffer, size_t count, * We'll be woken up again once below random_write_wakeup_thresh, * or when the calling thread is about to terminate. */ - wait_event_interruptible(random_write_wait, - kthread_freezable_should_stop(&frozen) || + wait_event_freezable(random_write_wait, + kthread_should_stop() || ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits); - if (!frozen) { - mix_pool_bytes(poolp, buffer, count); - credit_entropy_bits(poolp, entropy); - } + mix_pool_bytes(poolp, buffer, count); + credit_entropy_bits(poolp, entropy); } EXPORT_SYMBOL_GPL(add_hwgenerator_randomness); |