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 <[email protected]> --- drivers/hid/intel-ish-hid/ishtp/client.c | 46 +++++++++++++------------------- 1 file changed, 18 insertions(+), 28 deletions(-) diff --git a/drivers/hid/intel-ish-hid/ishtp/client.c b/drivers/hid/intel-ish-hid/ishtp/client.c index 69c9d43612ec..a4511ac8a87f 100644 --- a/drivers/hid/intel-ish-hid/ishtp/client.c +++ b/drivers/hid/intel-ish-hid/ishtp/client.c @@ -803,7 +803,7 @@ void ishtp_cl_send_msg(struct ishtp_device *dev, struct ishtp_cl *cl) * @ishtp_hdr: Pointer to message header * * Receive and dispatch ISHTP client messages. This function executes in ISR - * context + * or work queue context */ void recv_ishtp_cl_msg(struct ishtp_device *dev, struct ishtp_msg_hdr *ishtp_hdr) @@ -813,7 +813,6 @@ void recv_ishtp_cl_msg(struct ishtp_device *dev, struct ishtp_cl_rb *new_rb; unsigned char *buffer = NULL; struct ishtp_cl_rb *complete_rb = NULL; - unsigned long dev_flags; unsigned long flags; int rb_count; @@ -828,9 +827,9 @@ void recv_ishtp_cl_msg(struct ishtp_device *dev, goto eoi; } - spin_lock_irqsave(&dev->read_list_spinlock, dev_flags); + spin_lock_irqsave(&dev->read_list_spinlock, flags); if (list_empty(&dev->read_list.list)) { - spin_unlock_irqrestore(&dev->read_list_spinlock, dev_flags); + spin_unlock_irqrestore(&dev->read_list_spinlock, flags); goto eoi; } @@ -845,8 +844,7 @@ void recv_ishtp_cl_msg(struct ishtp_device *dev, /* If no Rx buffer is allocated, disband the rb */ if (rb->buffer.size == 0 || rb->buffer.data == NULL) { - spin_unlock_irqrestore(&dev->read_list_spinlock, - dev_flags); + spin_unlock_irqrestore(&dev->read_list_spinlock, flags); dev_err(&cl->device->dev, "Rx buffer is not allocated.\n"); list_del(&rb->list); @@ -862,8 +860,7 @@ void recv_ishtp_cl_msg(struct ishtp_device *dev, * back FC, so communication will be stuck anyway) */ if (rb->buffer.size < ishtp_hdr->length + rb->buf_idx) { - spin_unlock_irqrestore(&dev->read_list_spinlock, - dev_flags); + spin_unlock_irqrestore(&dev->read_list_spinlock, flags); dev_err(&cl->device->dev, "message overflow. size %d len %d idx %ld\n", rb->buffer.size, ishtp_hdr->length, @@ -889,14 +886,13 @@ void recv_ishtp_cl_msg(struct ishtp_device *dev, * the whole msg arrived, send a new FC, and add a new * rb buffer for the next coming msg */ - spin_lock_irqsave(&cl->free_list_spinlock, flags); + spin_lock(&cl->free_list_spinlock); if (!list_empty(&cl->free_rb_list.list)) { new_rb = list_entry(cl->free_rb_list.list.next, struct ishtp_cl_rb, list); list_del_init(&new_rb->list); - spin_unlock_irqrestore(&cl->free_list_spinlock, - flags); + spin_unlock(&cl->free_list_spinlock); new_rb->cl = cl; new_rb->buf_idx = 0; INIT_LIST_HEAD(&new_rb->list); @@ -905,8 +901,7 @@ void recv_ishtp_cl_msg(struct ishtp_device *dev, ishtp_hbm_cl_flow_control_req(dev, cl); } else { - spin_unlock_irqrestore(&cl->free_list_spinlock, - flags); + spin_unlock(&cl->free_list_spinlock); } } /* One more fragment in message (even if this was last) */ @@ -919,7 +914,7 @@ void recv_ishtp_cl_msg(struct ishtp_device *dev, break; } - spin_unlock_irqrestore(&dev->read_list_spinlock, dev_flags); + spin_unlock_irqrestore(&dev->read_list_spinlock, flags); /* If it's nobody's message, just read and discard it */ if (!buffer) { uint8_t rd_msg_buf[ISHTP_RD_MSG_BUF_SIZE]; @@ -945,7 +940,7 @@ void recv_ishtp_cl_msg(struct ishtp_device *dev, * @hbm: hbm buffer * * Receive and dispatch ISHTP client messages using DMA. This function executes - * in ISR context + * in ISR or work queue context */ void recv_ishtp_cl_msg_dma(struct ishtp_device *dev, void *msg, struct dma_xfer_hbm *hbm) @@ -955,12 +950,11 @@ void recv_ishtp_cl_msg_dma(struct ishtp_device *dev, void *msg, struct ishtp_cl_rb *new_rb; unsigned char *buffer = NULL; struct ishtp_cl_rb *complete_rb = NULL; - unsigned long dev_flags; unsigned long flags; - spin_lock_irqsave(&dev->read_list_spinlock, dev_flags); + spin_lock_irqsave(&dev->read_list_spinlock, flags); if (list_empty(&dev->read_list.list)) { - spin_unlock_irqrestore(&dev->read_list_spinlock, dev_flags); + spin_unlock_irqrestore(&dev->read_list_spinlock, flags); goto eoi; } @@ -975,8 +969,7 @@ void recv_ishtp_cl_msg_dma(struct ishtp_device *dev, void *msg, * If no Rx buffer is allocated, disband the rb */ if (rb->buffer.size == 0 || rb->buffer.data == NULL) { - spin_unlock_irqrestore(&dev->read_list_spinlock, - dev_flags); + spin_unlock_irqrestore(&dev->read_list_spinlock, flags); dev_err(&cl->device->dev, "response buffer is not allocated.\n"); list_del(&rb->list); @@ -992,8 +985,7 @@ void recv_ishtp_cl_msg_dma(struct ishtp_device *dev, void *msg, * back FC, so communication will be stuck anyway) */ if (rb->buffer.size < hbm->msg_length) { - spin_unlock_irqrestore(&dev->read_list_spinlock, - dev_flags); + spin_unlock_irqrestore(&dev->read_list_spinlock, flags); dev_err(&cl->device->dev, "message overflow. size %d len %d idx %ld\n", rb->buffer.size, hbm->msg_length, rb->buf_idx); @@ -1017,14 +1009,13 @@ void recv_ishtp_cl_msg_dma(struct ishtp_device *dev, void *msg, * the whole msg arrived, send a new FC, and add a new * rb buffer for the next coming msg */ - spin_lock_irqsave(&cl->free_list_spinlock, flags); + spin_lock(&cl->free_list_spinlock); if (!list_empty(&cl->free_rb_list.list)) { new_rb = list_entry(cl->free_rb_list.list.next, struct ishtp_cl_rb, list); list_del_init(&new_rb->list); - spin_unlock_irqrestore(&cl->free_list_spinlock, - flags); + spin_unlock(&cl->free_list_spinlock); new_rb->cl = cl; new_rb->buf_idx = 0; INIT_LIST_HEAD(&new_rb->list); @@ -1033,8 +1024,7 @@ void recv_ishtp_cl_msg_dma(struct ishtp_device *dev, void *msg, ishtp_hbm_cl_flow_control_req(dev, cl); } else { - spin_unlock_irqrestore(&cl->free_list_spinlock, - flags); + spin_unlock(&cl->free_list_spinlock); } /* One more fragment in message (this is always last) */ @@ -1047,7 +1037,7 @@ void recv_ishtp_cl_msg_dma(struct ishtp_device *dev, void *msg, break; } - spin_unlock_irqrestore(&dev->read_list_spinlock, dev_flags); + spin_unlock_irqrestore(&dev->read_list_spinlock, flags); /* If it's nobody's message, just read and discard it */ if (!buffer) { dev_err(dev->devc, "Dropped Rx (DMA) msg - no request\n"); -- 2.9.0
