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staging: axis-fifo: flush RX FIFO on read errors

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commit 82a051e2553b9e297cba82a975d9c538b882c79e upstream.

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

Commit c6e8d85fafa7 ("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: c6e8d85fafa7 ("staging: axis-fifo: Remove hardware resets for user errors")
Cc: stable@vger.kernel.org
Signed-off-by: Ovidiu Panait <ovidiu.panait.oss@gmail.com>
Link: https://lore.kernel.org/r/20250912101322.1282507-2-ovidiu.panait.oss@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ovidiu Panait 2025-09-12 13:13:22 +03:00 • committed by Greg Kroah-Hartman
commit 86bdd3deca
1 changed files with 11 additions and 7 deletions
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18
drivers/staging/axis-fifo/axis-fifo.c
View file

@ -400,6 +400,7 @@ 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;
@ -410,7 +411,7 @@ 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)) {
@ -419,11 +420,9 @@ 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
*/
@ -435,18 +434,23 @@ 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);
ret = bytes_available;
return bytes_available;
err_flush_rx:
while (words_available--)
ioread32(fifo->base_addr + XLLF_RDFD_OFFSET);
end_unlock:
mutex_unlock(&fifo->read_lock);