mei: me: do not reset when less than expected data is received

There is a race in ME hardware between data copy for host and interrupt
delivery. An interrupt can be delivered prior to whole data copied for the
host to read but rather then going trough the reset we just merely need to
wait for the next interrupt.

The bug is visible in read/write stress with multiple connections per client

This is a regression caused as a side effect of the commit:
commit 544f94601409653f07ae6e22d4a39e3a90dceead
mei: do not run reset flow from the interrupt thread

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Cc: stable <stable@vger.kernel.org> # 3.14
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/misc/mei/hw-me.c b/drivers/misc/mei/hw-me.c
index 7e769c59a4202d0004f4f2e2562b29ab238cd099..7145929cdb51a5ad8b4754fcc07641a542c4a66f 100644 (file)
--- a/drivers/misc/mei/hw-me.c
+++ b/drivers/misc/mei/hw-me.c
@@ -507,7 +507,16 @@ irqreturn_t mei_me_irq_thread_handler(int irq, void *dev_id)
        while (slots > 0) {
                dev_dbg(&dev->pdev->dev, "slots to read = %08x\n", slots);
                rets = mei_irq_read_handler(dev, &complete_list, &slots);
+               /* There is a race between ME write and interrupt delivery:
+                * Not all data is always available immediately after the
+                * interrupt, so try to read again on the next interrupt.
+                */
+               if (rets == -ENODATA)
+                       break;
+
                if (rets && dev->dev_state != MEI_DEV_RESETTING) {
+                       dev_err(&dev->pdev->dev, "mei_irq_read_handler ret = %d.\n",
+                                               rets);
                        schedule_work(&dev->reset_work);
                        goto end;
                }

diff --git a/drivers/misc/mei/interrupt.c b/drivers/misc/mei/interrupt.c
index 2fbf0c0625edbe7e839a9dcc7c44193625d8294c..f38a32addad01fe2fe3e2bd7790d0c99707cdd6b 100644 (file)
--- a/drivers/misc/mei/interrupt.c
+++ b/drivers/misc/mei/interrupt.c
@@ -351,7 +351,7 @@ int mei_irq_read_handler(struct mei_device *dev,
                dev_err(&dev->pdev->dev, "less data available than length=%08x.\n",
                                *slots);
                /* we can't read the message */
-               ret = -EBADMSG;
+               ret = -ENODATA;
                goto end;
        }