Commit 82a051e2 authored by Ovidiu Panait's avatar Ovidiu Panait Committed by Greg Kroah-Hartman
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staging: axis-fifo: flush RX FIFO on read errors 



Flush stale data from the RX FIFO in case of errors, to avoid reading
old data when new packets arrive.

Commit c6e8d85f ("staging: axis-fifo: Remove hardware resets for
user errors") removed full FIFO resets from the read error paths, which
fixed potential TX data losses, but introduced this RX issue.

Fixes: c6e8d85f ("staging: axis-fifo: Remove hardware resets for user errors")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarOvidiu Panait <ovidiu.panait.oss@gmail.com>
Link: https://lore.kernel.org/r/20250912101322.1282507-2-ovidiu.panait.oss@gmail.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6d07bee1

drivers/staging/axis-fifo/axis-fifo.c

+11 −7
Original line number Diff line number Diff line
@@ -227,6 +227,7 @@ static ssize_t axis_fifo_read(struct file *f, char __user *buf, 
	}



	bytes_available = ioread32(fifo->base_addr + XLLF_RLR_OFFSET);

	words_available = bytes_available / sizeof(u32);

	if (!bytes_available) {

		dev_err(fifo->dt_device, "received a packet of length 0\n");

		ret = -EIO;
@@ -237,7 +238,7 @@ static ssize_t axis_fifo_read(struct file *f, char __user *buf, 
		dev_err(fifo->dt_device, "user read buffer too small (available bytes=%zu user buffer bytes=%zu)\n",

			bytes_available, len);

		ret = -EINVAL;

		goto end_unlock;

		goto err_flush_rx;

	}



	if (bytes_available % sizeof(u32)) {
@@ -246,11 +247,9 @@ static ssize_t axis_fifo_read(struct file *f, char __user *buf, 
		 */

		dev_err(fifo->dt_device, "received a packet that isn't word-aligned\n");

		ret = -EIO;

		goto end_unlock;

		goto err_flush_rx;

	}



	words_available = bytes_available / sizeof(u32);



	/* read data into an intermediate buffer, copying the contents

	 * to userspace when the buffer is full

	 */
@@ -262,18 +261,23 @@ static ssize_t axis_fifo_read(struct file *f, char __user *buf, 
			tmp_buf[i] = ioread32(fifo->base_addr +

					      XLLF_RDFD_OFFSET);

		}

		words_available -= copy;



		if (copy_to_user(buf + copied * sizeof(u32), tmp_buf,

				 copy * sizeof(u32))) {

			ret = -EFAULT;

			goto end_unlock;

			goto err_flush_rx;

		}



		copied += copy;

		words_available -= copy;

	}

	mutex_unlock(&fifo->read_lock);



	return bytes_available;



	ret = bytes_available;

err_flush_rx:

	while (words_available--)

		ioread32(fifo->base_addr + XLLF_RDFD_OFFSET);



end_unlock:

	mutex_unlock(&fifo->read_lock);