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authorBjorn Andersson <bjorn.andersson@linaro.org>2018-02-13 11:04:11 -0800
committerBjorn Andersson <bjorn.andersson@linaro.org>2018-03-20 10:52:17 +0800
commit33e3820dda8876792bd8135db633c741a07263be (patch)
tree263a1d4b53c52ba6860056d00fa6f9d9edb4c570 /drivers/rpmsg
parentbe5acd246daa04edad9d758b8be37e5e2f989243 (diff)
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rpmsg: smd: Use spinlock in tx path
By switching the tx_lock to a spinlock we allow clients to use rpmsg_trysend() from atomic context. The mutex was interruptable as it was previously held for the duration of some client waiting for available space in the FIFO, but this was recently changed to only be held temporarily - allowing us to replace it with a spinlock. Tested-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Diffstat (limited to 'drivers/rpmsg')
-rw-r--r--drivers/rpmsg/qcom_smd.c21
1 files changed, 11 insertions, 10 deletions
diff --git a/drivers/rpmsg/qcom_smd.c b/drivers/rpmsg/qcom_smd.c
index ff8101a768bc..76b1c00b4a19 100644
--- a/drivers/rpmsg/qcom_smd.c
+++ b/drivers/rpmsg/qcom_smd.c
@@ -205,7 +205,7 @@ struct qcom_smd_channel {
struct smd_channel_info_pair *info;
struct smd_channel_info_word_pair *info_word;
- struct mutex tx_lock;
+ spinlock_t tx_lock;
wait_queue_head_t fblockread_event;
void *tx_fifo;
@@ -729,6 +729,7 @@ static int __qcom_smd_send(struct qcom_smd_channel *channel, const void *data,
{
__le32 hdr[5] = { cpu_to_le32(len), };
int tlen = sizeof(hdr) + len;
+ unsigned long flags;
int ret;
/* Word aligned channels only accept word size aligned data */
@@ -739,9 +740,11 @@ static int __qcom_smd_send(struct qcom_smd_channel *channel, const void *data,
if (tlen >= channel->fifo_size)
return -EINVAL;
- ret = mutex_lock_interruptible(&channel->tx_lock);
- if (ret)
- return ret;
+ /* Highlight the fact that if we enter the loop below we might sleep */
+ if (wait)
+ might_sleep();
+
+ spin_lock_irqsave(&channel->tx_lock, flags);
while (qcom_smd_get_tx_avail(channel) < tlen &&
channel->state == SMD_CHANNEL_OPENED) {
@@ -753,7 +756,7 @@ static int __qcom_smd_send(struct qcom_smd_channel *channel, const void *data,
SET_TX_CHANNEL_FLAG(channel, fBLOCKREADINTR, 0);
/* Wait without holding the tx_lock */
- mutex_unlock(&channel->tx_lock);
+ spin_unlock_irqrestore(&channel->tx_lock, flags);
ret = wait_event_interruptible(channel->fblockread_event,
qcom_smd_get_tx_avail(channel) >= tlen ||
@@ -761,9 +764,7 @@ static int __qcom_smd_send(struct qcom_smd_channel *channel, const void *data,
if (ret)
return ret;
- ret = mutex_lock_interruptible(&channel->tx_lock);
- if (ret)
- return ret;
+ spin_lock_irqsave(&channel->tx_lock, flags);
SET_TX_CHANNEL_FLAG(channel, fBLOCKREADINTR, 1);
}
@@ -787,7 +788,7 @@ static int __qcom_smd_send(struct qcom_smd_channel *channel, const void *data,
qcom_smd_signal_channel(channel);
out_unlock:
- mutex_unlock(&channel->tx_lock);
+ spin_unlock_irqrestore(&channel->tx_lock, flags);
return ret;
}
@@ -1090,7 +1091,7 @@ static struct qcom_smd_channel *qcom_smd_create_channel(struct qcom_smd_edge *ed
if (!channel->name)
return ERR_PTR(-ENOMEM);
- mutex_init(&channel->tx_lock);
+ spin_lock_init(&channel->tx_lock);
spin_lock_init(&channel->recv_lock);
init_waitqueue_head(&channel->fblockread_event);
init_waitqueue_head(&channel->state_change_event);