Patch "cxl: Force context lock during EEH flow" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

cxl: Force context lock during EEH flow

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
cxl-force-context-lock-during-eeh-flow.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Vaibhav Jain <[email protected]>
Date: Thu, 27 Apr 2017 10:53:25 +0530
Subject: cxl: Force context lock during EEH flow

From: Vaibhav Jain <[email protected]>

commit ea9a26d117cf0637c71d3e0076f4a124bf5859df upstream.

During an eeh event when the cxl card is fenced and card sysfs attr perst_reloads_same_image is set following warning message is seen in the kernel logs:

Adapter context unlocked with 0 active contexts

  ------------[ cut here ]------------
  WARNING: CPU: 12 PID: 627 at
  ../drivers/misc/cxl/main.c:325 cxl_adapter_context_unlock+0x60/0x80 [cxl]

Even though this warning is harmless, it clutters the kernel log during an eeh event. This warning is triggered as the EEH callback cxl_pci_error_detected doesn't obtain a context-lock before forcibly detaching all active context and when context-lock is released during call to cxl_configure_adapter from cxl_pci_slot_reset, a warning in cxl_adapter_context_unlock is triggered.

To fix this warning, we acquire the adapter context-lock via cxl_adapter_context_lock() in the eeh callback cxl_pci_error_detected() once all the virtual AFU PHBs are notified and their contexts detached. The context-lock is released in cxl_pci_slot_reset() after the adapter is successfully reconfigured and before the we call the slot_reset callback on slice attached device-drivers.

---
 drivers/misc/cxl/pci.c |   19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

@@ -1496,8 +1496,6 @@ static int cxl_configure_adapter(struct
 	if ((rc = cxl_native_register_psl_err_irq(adapter)))
 		goto err;
 
-	/* Release the context lock as adapter is configured */
-	cxl_adapter_context_unlock(adapter);
 	return 0;
 
 err:

@@ -1596,6 +1594,9 @@ static struct cxl *cxl_pci_init_adapter(
 	if ((rc = cxl_sysfs_adapter_add(adapter)))
 		goto err_put1;
 
+	/* Release the context lock as adapter is configured */
+	cxl_adapter_context_unlock(adapter);
+
 	return adapter;
 
 err_put1:

@@ -1893,6 +1894,13 @@ static pci_ers_result_t cxl_pci_error_de
 		cxl_ops->afu_deactivate_mode(afu, afu->current_mode);
 		pci_deconfigure_afu(afu);
 	}
+
+	/* should take the context lock here */
+	if (cxl_adapter_context_lock(adapter) != 0)
+		dev_warn(&adapter->dev,
+			 "Couldn't take context lock with %d active-contexts\n",
+			 atomic_read(&adapter->contexts_num));
+
 	cxl_deconfigure_adapter(adapter);
 
 	return result;

@@ -1911,6 +1919,13 @@ static pci_ers_result_t cxl_pci_slot_res
 	if (cxl_configure_adapter(adapter, pdev))
 		goto err;
 
+	/*
+	 * Unlock context activation for the adapter. Ideally this should be
+	 * done in cxl_pci_resume but cxlflash module tries to activate the
+	 * master context as part of slot_reset callback.
+	 */
+	cxl_adapter_context_unlock(adapter);
+
 	for (i = 0; i < adapter->slices; i++) {
 		afu = adapter->afu[i];
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/cxl-force-context-lock-during-eeh-flow.patch queue-4.9/cxl-route-eeh-events-to-all-drivers-in-cxl_pci_error_detected.patch