[PATCH 4.9 56/59] crypto: mxs-dcp - Fix wait logic on chan threads

Greg Kroah-Hartman
2018-10-08T18:40:33Z

From: Leonard Crestez <leonard.crestez@nxp.com>

commit d80771c08363ad7fbf0f56f5301e7ca65065c582 upstream.

When compiling with CONFIG_DEBUG_ATOMIC_SLEEP=y the mxs-dcp driver
prints warnings such as:

WARNING: CPU: 0 PID: 120 at kernel/sched/core.c:7736 __might_sleep+0x98/0x9c
do not call blocking ops when !TASK_RUNNING; state=1 set at [<8081978c>] dcp_chan_thread_sha+0x3c/0x2ec

The problem is that blocking ops will manipulate current->state
themselves so it is not allowed to call them between
set_current_state(TASK_INTERRUPTIBLE) and schedule().

Fix this by converting the per-chan mutex to a spinlock (it only
protects tiny list ops anyway) and rearranging the wait logic so that
callbacks are called current->state as TASK_RUNNING. Those callbacks
will indeed call blocking ops themselves so this is required.

Cc: <stable@vger.kernel.org>
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/crypto/mxs-dcp.c | 53 ++++++++++++++++++++++++++---------------------
1 file changed, 30 insertions(+), 23 deletions(-)

--- a/drivers/crypto/mxs-dcp.c
+++ b/drivers/crypto/mxs-dcp.c
@@ -63,7 +63,7 @@ struct dcp {
struct dcp_coherent_block *coh;

struct completion completion[DCP_MAX_CHANS];
- struct mutex mutex[DCP_MAX_CHANS];
+ spinlock_t lock[DCP_MAX_CHANS];
struct task_struct *thread[DCP_MAX_CHANS];
struct crypto_queue queue[DCP_MAX_CHANS];
};
@@ -349,13 +349,20 @@ static int dcp_chan_thread_aes(void *dat

int ret;

- do {
- __set_current_state(TASK_INTERRUPTIBLE);
+ while (!kthread_should_stop()) {
+ set_current_state(TASK_INTERRUPTIBLE);

- mutex_lock(&sdcp->mutex[chan]);
+ spin_lock(&sdcp->lock[chan]);
backlog = crypto_get_backlog(&sdcp->queue[chan]);
arq = crypto_dequeue_request(&sdcp->queue[chan]);
- mutex_unlock(&sdcp->mutex[chan]);
+ spin_unlock(&sdcp->lock[chan]);
+
+ if (!backlog && !arq) {
+ schedule();
+ continue;
+ }
+
+ set_current_state(TASK_RUNNING);

if (backlog)
backlog->complete(backlog, -EINPROGRESS);
@@ -363,11 +370,8 @@ static int dcp_chan_thread_aes(void *dat
if (arq) {
ret = mxs_dcp_aes_block_crypt(arq);
arq->complete(arq, ret);
- continue;
}
-
- schedule();
- } while (!kthread_should_stop());
+ }

return 0;
}
@@ -409,9 +413,9 @@ static int mxs_dcp_aes_enqueue(struct ab
rctx->ecb = ecb;
actx->chan = DCP_CHAN_CRYPTO;

- mutex_lock(&sdcp->mutex[actx->chan]);
+ spin_lock(&sdcp->lock[actx->chan]);
ret = crypto_enqueue_request(&sdcp->queue[actx->chan], &req->base);
- mutex_unlock(&sdcp->mutex[actx->chan]);
+ spin_unlock(&sdcp->lock[actx->chan]);

wake_up_process(sdcp->thread[actx->chan]);

@@ -640,13 +644,20 @@ static int dcp_chan_thread_sha(void *dat
struct ahash_request *req;
int ret, fini;

- do {
- __set_current_state(TASK_INTERRUPTIBLE);
+ while (!kthread_should_stop()) {
+ set_current_state(TASK_INTERRUPTIBLE);

- mutex_lock(&sdcp->mutex[chan]);
+ spin_lock(&sdcp->lock[chan]);
backlog = crypto_get_backlog(&sdcp->queue[chan]);
arq = crypto_dequeue_request(&sdcp->queue[chan]);
- mutex_unlock(&sdcp->mutex[chan]);
+ spin_unlock(&sdcp->lock[chan]);
+
+ if (!backlog && !arq) {
+ schedule();
+ continue;
+ }
+
+ set_current_state(TASK_RUNNING);

if (backlog)
backlog->complete(backlog, -EINPROGRESS);
@@ -658,12 +669,8 @@ static int dcp_chan_thread_sha(void *dat
ret = dcp_sha_req_to_buf(arq);
fini = rctx->fini;
arq->complete(arq, ret);
- if (!fini)
- continue;
}
-
- schedule();
- } while (!kthread_should_stop());
+ }

return 0;
}
@@ -721,9 +728,9 @@ static int dcp_sha_update_fx(struct ahas
rctx->init = 1;
}

- mutex_lock(&sdcp->mutex[actx->chan]);
+ spin_lock(&sdcp->lock[actx->chan]);
ret = crypto_enqueue_request(&sdcp->queue[actx->chan], &req->base);
- mutex_unlock(&sdcp->mutex[actx->chan]);
+ spin_unlock(&sdcp->lock[actx->chan]);

wake_up_process(sdcp->thread[actx->chan]);
mutex_unlock(&actx->mutex);
@@ -979,7 +986,7 @@ static int mxs_dcp_probe(struct platform
platform_set_drvdata(pdev, sdcp);

for (i = 0; i < DCP_MAX_CHANS; i++) {
- mutex_init(&sdcp->mutex[i]);
+ spin_lock_init(&sdcp->lock[i]);
init_completion(&sdcp->completion[i]);
crypto_init_queue(&sdcp->queue[i], 50);
}