[char-misc-next 2/4] mei: pxp: recover from recv fail under memory pressure

Tomas Winkler
2023-10-11T11:02:27Z

From: Alexander Usyskin <alexander.usyskin@intel.com>

Under memory pressure recv fails due to kmalloc failure,
and if drivers(pxp) retry send/receive, send blocks
indefinitely.
Send without recv leaves the channel in a bad state.

Retry send attempt after small timeout and reset the channel if
the retry failed on kmalloc failure too.

Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Alan Previn <alan.previn.teres.alexis@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
---
drivers/misc/mei/pxp/mei_pxp.c | 25 ++++++++++++++++++++++++-
1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/mei/pxp/mei_pxp.c b/drivers/misc/mei/pxp/mei_pxp.c
index 2dcb9169e404c3bcbbccc7b4..c6cdd6a47308ebcc72f34c38 100644
--- a/drivers/misc/mei/pxp/mei_pxp.c
+++ b/drivers/misc/mei/pxp/mei_pxp.c
@@ -11,6 +11,7 @@
* negotiation messages to ME FW command payloads and vice versa.
*/

+#include <linux/delay.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/mei.h>
@@ -61,16 +62,38 @@ mei_pxp_receive_message(struct device *dev, void *buffer, size_t size)
{
struct mei_cl_device *cldev;
ssize_t byte;
+ bool retry = false;

if (!dev || !buffer)
return -EINVAL;

cldev = to_mei_cl_device(dev);

+retry:
byte = mei_cldev_recv(cldev, buffer, size);
if (byte < 0) {
dev_dbg(dev, "mei_cldev_recv failed. %zd\n", byte);
- return byte;
+ if (byte != -ENOMEM)
+ return byte;
+
+ /* Retry the read when pages are reclaimed */
+ msleep(20);
+ if (!retry) {
+ retry = true;
+ goto retry;
+ } else {
+ dev_warn(dev, "No memory on data receive after retry, trying to reset the channel...\n");
+ byte = mei_cldev_disable(cldev);
+ if (byte < 0)
+ dev_warn(dev, "mei_cldev_disable failed. %zd\n", byte);
+ /*
+ * Explicitly ignoring disable failure,
+ * enable may fix the states and succeed
+ */
+ byte = mei_cldev_enable(cldev);
+ if (byte < 0)
+ dev_err(dev, "mei_cldev_enable failed. %zd\n", byte);
+ }
}

return byte;
--
2.41.0