Le 03/02/2017 à 07:57, Vaibhav Jain a écrit :
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:
[ 60.622727] Adapter context unlocked with 0 active contexts
[ 60.622762] ------------[ cut here ]------------
[ 60.622771] 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 and also prevent activation of any context during
eeh the patch introduces a new function cxl_adapter_context_force_lock
that would forcefully acquire the context_lock and warn if any active
contexts exists when this happens. After the EEH flow concludes with
call to cxl_pci_resume the context-lock is released with a call to
cxl_adapter_context_unlock.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 70b565bbdb91("cxl: Prevent adapter reset if an active context exists")
Reported-by: Andrew Donnellan <andrew.donnellan@xxxxxxxxxxx>
Signed-off-by: Vaibhav Jain <vaibhav@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Andrew Donnellan <andrew.donnellan@xxxxxxxxxxx>
---
drivers/misc/cxl/cxl.h | 3 +++
drivers/misc/cxl/main.c | 10 ++++++++++
drivers/misc/cxl/pci.c | 18 ++++++++++++++++--
3 files changed, 29 insertions(+), 2 deletions(-)
diff --git a/drivers/misc/cxl/cxl.h b/drivers/misc/cxl/cxl.h
index b24d767..34d2ca0 100644
--- a/drivers/misc/cxl/cxl.h
+++ b/drivers/misc/cxl/cxl.h
@@ -970,4 +970,7 @@ int cxl_adapter_context_lock(struct cxl *adapter);
/* Unlock the contexts-lock if taken. Warn and force unlock otherwise */
void cxl_adapter_context_unlock(struct cxl *adapter);
+/* Force contexts-lock to be taken */
+void cxl_adapter_context_force_lock(struct cxl *adapter);
+
#endif
diff --git a/drivers/misc/cxl/main.c b/drivers/misc/cxl/main.c
index 62e0dfb..1754a0c 100644
--- a/drivers/misc/cxl/main.c
+++ b/drivers/misc/cxl/main.c
@@ -301,6 +301,16 @@ void cxl_adapter_context_put(struct cxl *adapter)
atomic_dec_if_positive(&adapter->contexts_num);
}
+void cxl_adapter_context_force_lock(struct cxl *adapter)
+{
+ int count = atomic_read(&adapter->contexts_num);
+
+ if (count > 0)
+ pr_warn("Forcing context lock with %d active contexts\n",
+ count);
+ atomic_set(&adapter->contexts_num, -1);
+}
+
int cxl_adapter_context_lock(struct cxl *adapter)
{
int rc;
diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index 80a87ab..d76fd4d 100644
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c
@@ -1487,8 +1487,6 @@ static int cxl_configure_adapter(struct cxl *adapter, struct pci_dev *dev)
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:
@@ -1587,6 +1585,9 @@ static struct cxl *cxl_pci_init_adapter(struct pci_dev *dev)
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:
@@ -1607,6 +1608,9 @@ static void cxl_pci_remove_adapter(struct cxl *adapter)
{
pr_devel("cxl_remove_adapter\n");
+ /* Forcibly take the adapter context lock */
+ cxl_adapter_context_force_lock(adapter);
+
cxl_sysfs_adapter_remove(adapter);
cxl_debugfs_adapter_remove(adapter);
@@ -1778,6 +1782,9 @@ static pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev,
*/
schedule();
+ /* forcibly take the context lock to prevent new context activation */
+ cxl_adapter_context_force_lock(adapter);
+
I'm not a fan of the "force lock" call and I'm not convinced it's
needed. When an EEH is triggered, we'll force-detach all the contexts.
So that in itself should bring the counter of active contexts to 0. So
why not just add a cxl_adapter_context_lock() call at the end of
cxl_pci_error_detected()? The lock would be released in
cxl_configure_adapter when cxl_pci_slot_reset() is called, as is already
the case with the current code.
(as a side note, I don't believe the code is racy and that we need to
add extra protection to avoid context activation while
cxl_pci_error_detected() is called. We can talk about it if needed)
Fred
/* If we're permanently dead, give up. */
if (state == pci_channel_io_perm_failure) {
/* Tell the AFU drivers; but we don't care what they
@@ -1879,11 +1886,15 @@ static pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev,
/* Only continue if everyone agrees on NEED_RESET */
if (result != PCI_ERS_RESULT_NEED_RESET)
return result;
+ }
+ for (i = 0; i < adapter->slices; i++) {
+ afu = adapter->afu[i];
cxl_context_detach_all(afu);
cxl_ops->afu_deactivate_mode(afu, afu->current_mode);
pci_deconfigure_afu(afu);
}
+
cxl_deconfigure_adapter(adapter);
return result;
@@ -1979,6 +1990,9 @@ static void cxl_pci_resume(struct pci_dev *pdev)
afu_dev->driver->err_handler->resume(afu_dev);
}
}
+
+ /* Unlock context activation for the adapter */
+ cxl_adapter_context_unlock(adapter);
}
static const struct pci_error_handlers cxl_err_handler = {
--
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