mirror of https://gitee.com/openkylin/linux.git
HID: intel_ish-hid: clarify locking in client code
I was trying to understand this code while working on a warning fix and the locking made no sense: spin_lock_irqsave() is pointless when run inside of an interrupt handler or nested inside of another spin_lock_irq() or spin_lock_irqsave(). Here it turned out that the comment above the function is wrong, as both recv_ishtp_cl_msg_dma() and recv_ishtp_cl_msg() can in fact be called from a work queue rather than an ISR, so we do have to use the irqsave() version once. This fixes the comments accordingly, removes the misleading 'dev_flags' variable and modifies the inner spinlock to not use 'irqsave'. No functional change is intended, this is just for readability and it slightly simplifies the object code. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
This commit is contained in:
Arnd Bergmann
Jiri Kosina
parent
1260662fa3
commit
538be0aa86
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@ -803,7 +803,7 @@ void ishtp_cl_send_msg(struct ishtp_device *dev, struct ishtp_cl *cl)
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* @ishtp_hdr: Pointer to message header
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*
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* Receive and dispatch ISHTP client messages. This function executes in ISR
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* context
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* or work queue context
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*/
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void recv_ishtp_cl_msg(struct ishtp_device *dev,
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struct ishtp_msg_hdr *ishtp_hdr)
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@ -813,7 +813,6 @@ void recv_ishtp_cl_msg(struct ishtp_device *dev,
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struct ishtp_cl_rb *new_rb;
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unsigned char *buffer = NULL;
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struct ishtp_cl_rb *complete_rb = NULL;
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unsigned long dev_flags;
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unsigned long flags;
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int rb_count;
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@ -828,7 +827,7 @@ void recv_ishtp_cl_msg(struct ishtp_device *dev,
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goto eoi;
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}
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spin_lock_irqsave(&dev->read_list_spinlock, dev_flags);
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spin_lock_irqsave(&dev->read_list_spinlock, flags);
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rb_count = -1;
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list_for_each_entry(rb, &dev->read_list.list, list) {
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++rb_count;
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@ -840,8 +839,7 @@ void recv_ishtp_cl_msg(struct ishtp_device *dev,
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/* If no Rx buffer is allocated, disband the rb */
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if (rb->buffer.size == 0 || rb->buffer.data == NULL) {
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spin_unlock_irqrestore(&dev->read_list_spinlock,
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dev_flags);
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spin_unlock_irqrestore(&dev->read_list_spinlock, flags);
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dev_err(&cl->device->dev,
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"Rx buffer is not allocated.\n");
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list_del(&rb->list);
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@ -857,8 +855,7 @@ void recv_ishtp_cl_msg(struct ishtp_device *dev,
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* back FC, so communication will be stuck anyway)
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*/
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if (rb->buffer.size < ishtp_hdr->length + rb->buf_idx) {
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spin_unlock_irqrestore(&dev->read_list_spinlock,
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dev_flags);
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spin_unlock_irqrestore(&dev->read_list_spinlock, flags);
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dev_err(&cl->device->dev,
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"message overflow. size %d len %d idx %ld\n",
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rb->buffer.size, ishtp_hdr->length,
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@ -884,14 +881,13 @@ void recv_ishtp_cl_msg(struct ishtp_device *dev,
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* the whole msg arrived, send a new FC, and add a new
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* rb buffer for the next coming msg
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*/
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spin_lock_irqsave(&cl->free_list_spinlock, flags);
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spin_lock(&cl->free_list_spinlock);
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if (!list_empty(&cl->free_rb_list.list)) {
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new_rb = list_entry(cl->free_rb_list.list.next,
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struct ishtp_cl_rb, list);
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list_del_init(&new_rb->list);
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spin_unlock_irqrestore(&cl->free_list_spinlock,
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flags);
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spin_unlock(&cl->free_list_spinlock);
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new_rb->cl = cl;
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new_rb->buf_idx = 0;
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INIT_LIST_HEAD(&new_rb->list);
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@ -900,8 +896,7 @@ void recv_ishtp_cl_msg(struct ishtp_device *dev,
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ishtp_hbm_cl_flow_control_req(dev, cl);
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} else {
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spin_unlock_irqrestore(&cl->free_list_spinlock,
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flags);
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spin_unlock(&cl->free_list_spinlock);
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}
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}
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/* One more fragment in message (even if this was last) */
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@ -914,7 +909,7 @@ void recv_ishtp_cl_msg(struct ishtp_device *dev,
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break;
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}
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spin_unlock_irqrestore(&dev->read_list_spinlock, dev_flags);
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spin_unlock_irqrestore(&dev->read_list_spinlock, flags);
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/* If it's nobody's message, just read and discard it */
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if (!buffer) {
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uint8_t rd_msg_buf[ISHTP_RD_MSG_BUF_SIZE];
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@ -941,7 +936,7 @@ void recv_ishtp_cl_msg(struct ishtp_device *dev,
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* @hbm: hbm buffer
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*
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* Receive and dispatch ISHTP client messages using DMA. This function executes
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* in ISR context
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* in ISR or work queue context
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*/
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void recv_ishtp_cl_msg_dma(struct ishtp_device *dev, void *msg,
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struct dma_xfer_hbm *hbm)
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@ -951,10 +946,10 @@ void recv_ishtp_cl_msg_dma(struct ishtp_device *dev, void *msg,
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struct ishtp_cl_rb *new_rb;
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unsigned char *buffer = NULL;
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struct ishtp_cl_rb *complete_rb = NULL;
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unsigned long dev_flags;
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unsigned long flags;
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spin_lock_irqsave(&dev->read_list_spinlock, dev_flags);
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spin_lock_irqsave(&dev->read_list_spinlock, flags);
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list_for_each_entry(rb, &dev->read_list.list, list) {
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cl = rb->cl;
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if (!cl || !(cl->host_client_id == hbm->host_client_id &&
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@ -966,8 +961,7 @@ void recv_ishtp_cl_msg_dma(struct ishtp_device *dev, void *msg,
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* If no Rx buffer is allocated, disband the rb
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*/
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if (rb->buffer.size == 0 || rb->buffer.data == NULL) {
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spin_unlock_irqrestore(&dev->read_list_spinlock,
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dev_flags);
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spin_unlock_irqrestore(&dev->read_list_spinlock, flags);
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dev_err(&cl->device->dev,
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"response buffer is not allocated.\n");
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list_del(&rb->list);
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@ -983,8 +977,7 @@ void recv_ishtp_cl_msg_dma(struct ishtp_device *dev, void *msg,
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* back FC, so communication will be stuck anyway)
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*/
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if (rb->buffer.size < hbm->msg_length) {
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spin_unlock_irqrestore(&dev->read_list_spinlock,
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dev_flags);
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spin_unlock_irqrestore(&dev->read_list_spinlock, flags);
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dev_err(&cl->device->dev,
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"message overflow. size %d len %d idx %ld\n",
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rb->buffer.size, hbm->msg_length, rb->buf_idx);
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@ -1008,14 +1001,13 @@ void recv_ishtp_cl_msg_dma(struct ishtp_device *dev, void *msg,
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* the whole msg arrived, send a new FC, and add a new
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* rb buffer for the next coming msg
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*/
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spin_lock_irqsave(&cl->free_list_spinlock, flags);
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spin_lock(&cl->free_list_spinlock);
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if (!list_empty(&cl->free_rb_list.list)) {
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new_rb = list_entry(cl->free_rb_list.list.next,
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struct ishtp_cl_rb, list);
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list_del_init(&new_rb->list);
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spin_unlock_irqrestore(&cl->free_list_spinlock,
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flags);
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spin_unlock(&cl->free_list_spinlock);
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new_rb->cl = cl;
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new_rb->buf_idx = 0;
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INIT_LIST_HEAD(&new_rb->list);
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@ -1024,8 +1016,7 @@ void recv_ishtp_cl_msg_dma(struct ishtp_device *dev, void *msg,
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ishtp_hbm_cl_flow_control_req(dev, cl);
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} else {
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spin_unlock_irqrestore(&cl->free_list_spinlock,
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flags);
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spin_unlock(&cl->free_list_spinlock);
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}
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/* One more fragment in message (this is always last) */
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@ -1038,7 +1029,7 @@ void recv_ishtp_cl_msg_dma(struct ishtp_device *dev, void *msg,
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break;
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}
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spin_unlock_irqrestore(&dev->read_list_spinlock, dev_flags);
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spin_unlock_irqrestore(&dev->read_list_spinlock, flags);
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/* If it's nobody's message, just read and discard it */
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if (!buffer) {
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dev_err(dev->devc, "Dropped Rx (DMA) msg - no request\n");
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