diff mbox series

[v1,1/1] PCI/ERR: don't clobber status after reset_link()

Message ID 20201009025251.2360659-1-hedi.berriche@hpe.com
State New
Headers show
Series [v1,1/1] PCI/ERR: don't clobber status after reset_link() | expand

Commit Message

Hedi Berriche Oct. 9, 2020, 2:52 a.m. UTC
Commit 6d2c89441571 ("PCI/ERR: Update error status after reset_link()")
changed pcie_do_recovery() so that status is updated with the return
value from reset_link(); this was to fix the problem where we would
wrongly report recovery failure, despite a successful reset_link(),
whenever the initial error status is PCI_ERS_RESULT_DISCONNECT or
PCI_ERS_RESULT_NO_AER_DRIVER.

Unfortunately this breaks the flow of pcie_do_recovery() as it prevents
the actions needed when the initial error is PCI_ERS_RESULT_CAN_RECOVER
or PCI_ERS_RESULT_NEED_RESET from taking place which causes error
recovery to fail.

Don't clobber status after reset_link() to restore the intended flow in
pcie_do_recovery().

Fix the original problem by saving the return value from reset_link()
and use it later on to decide whether error recovery should be deemed
successful in the scenarios where the initial error status is
PCI_ERS_RESULT_{DISCONNECT,NO_AER_DRIVER}.

Fixes: 6d2c89441571 ("PCI/ERR: Update error status after reset_link()")
Signed-off-by: Hedi Berriche <hedi.berriche@hpe.com>
Cc: Russ Anderson <rja@hpe.com>
Cc: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Joerg Roedel <jroedel@suse.com>

Cc: stable@kernel.org # v5.7+
---
 drivers/pci/pcie/err.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

Comments

Raj, Ashok Oct. 9, 2020, 3:46 a.m. UTC | #1
On Fri, Oct 09, 2020 at 03:52:51AM +0100, Hedi Berriche wrote:
> Commit 6d2c89441571 ("PCI/ERR: Update error status after reset_link()")
> changed pcie_do_recovery() so that status is updated with the return
> value from reset_link(); this was to fix the problem where we would
> wrongly report recovery failure, despite a successful reset_link(),
> whenever the initial error status is PCI_ERS_RESULT_DISCONNECT or
> PCI_ERS_RESULT_NO_AER_DRIVER.
> 
> Unfortunately this breaks the flow of pcie_do_recovery() as it prevents

What is the reference to "this breaks" above?  

> the actions needed when the initial error is PCI_ERS_RESULT_CAN_RECOVER
> or PCI_ERS_RESULT_NEED_RESET from taking place which causes error
> recovery to fail.
> 
> Don't clobber status after reset_link() to restore the intended flow in
> pcie_do_recovery().
> 
> Fix the original problem by saving the return value from reset_link()
> and use it later on to decide whether error recovery should be deemed
> successful in the scenarios where the initial error status is
> PCI_ERS_RESULT_{DISCONNECT,NO_AER_DRIVER}.

I would rather rephrase the above to make it clear what is being proposed.
Since the description seems to talk about the old problem and new solution
all mixed up.

> 
> Fixes: 6d2c89441571 ("PCI/ERR: Update error status after reset_link()")
> Signed-off-by: Hedi Berriche <hedi.berriche@hpe.com>
> Cc: Russ Anderson <rja@hpe.com>
> Cc: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: Ashok Raj <ashok.raj@intel.com>
> Cc: Keith Busch <keith.busch@intel.com>
> Cc: Joerg Roedel <jroedel@suse.com>
> 
> Cc: stable@kernel.org # v5.7+
> ---
>  drivers/pci/pcie/err.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
> index c543f419d8f9..dbd0b56bd6c1 100644
> --- a/drivers/pci/pcie/err.c
> +++ b/drivers/pci/pcie/err.c
> @@ -150,7 +150,7 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
>  			pci_channel_state_t state,
>  			pci_ers_result_t (*reset_link)(struct pci_dev *pdev))
>  {
> -	pci_ers_result_t status = PCI_ERS_RESULT_CAN_RECOVER;
> +	pci_ers_result_t post_reset_status, status = PCI_ERS_RESULT_CAN_RECOVER;

why call it post_reset_status? 

>  	struct pci_bus *bus;
>  
>  	/*
> @@ -165,8 +165,8 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
>  	pci_dbg(dev, "broadcast error_detected message\n");
>  	if (state == pci_channel_io_frozen) {
>  		pci_walk_bus(bus, report_frozen_detected, &status);
> -		status = reset_link(dev);
> -		if (status != PCI_ERS_RESULT_RECOVERED) {
> +		post_reset_status = reset_link(dev);
> +		if (post_reset_status != PCI_ERS_RESULT_RECOVERED) {
>  			pci_warn(dev, "link reset failed\n");
>  			goto failed;
>  		}
> @@ -174,6 +174,13 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
>  		pci_walk_bus(bus, report_normal_detected, &status);
>  	}
>  
> +	if ((status == PCI_ERS_RESULT_DISCONNECT ||
> +	     status == PCI_ERS_RESULT_NO_AER_DRIVER) &&
> +	     post_reset_status == PCI_ERS_RESULT_RECOVERED) {
> +		/* error recovery succeeded thanks to reset_link() */
> +		status = PCI_ERS_RESULT_RECOVERED;
> +	}
> +
>  	if (status == PCI_ERS_RESULT_CAN_RECOVER) {
>  		status = PCI_ERS_RESULT_RECOVERED;
>  		pci_dbg(dev, "broadcast mmio_enabled message\n");
> -- 
> 2.28.0
>
Hedi Berriche Oct. 9, 2020, 4:05 a.m. UTC | #2
On Fri, Oct 09, 2020 at 04:46 Raj, Ashok wrote:

Hi Ashok,

Thanks for looking into this.

>On Fri, Oct 09, 2020 at 03:52:51AM +0100, Hedi Berriche wrote:
>> Commit 6d2c89441571 ("PCI/ERR: Update error status after reset_link()")
>> changed pcie_do_recovery() so that status is updated with the return
>> value from reset_link(); this was to fix the problem where we would
>> wrongly report recovery failure, despite a successful reset_link(),
>> whenever the initial error status is PCI_ERS_RESULT_DISCONNECT or
>> PCI_ERS_RESULT_NO_AER_DRIVER.
>>
>> Unfortunately this breaks the flow of pcie_do_recovery() as it prevents
>
>What is the reference to "this breaks" above?

The code change introduced by commit 6d2c89441571; would

     "this code change" instead of "this breaks"

work better? If not, I can also rephrase the whole paragraph along the following lines:

Commit 6d2c89441571 ("PCI/ERR: Update error status after reset_link()") breaks the flow
of pcie_do_recovery() as it prevents the actions needed when the initial error is
PCI_ERS_RESULT_CAN_RECOVER or PCI_ERS_RESULT_NEED_RESET from taking place which causes
error recovery to fail.

... and do away with the first paragraph.

>> the actions needed when the initial error is PCI_ERS_RESULT_CAN_RECOVER
>> or PCI_ERS_RESULT_NEED_RESET from taking place which causes error
>> recovery to fail.
>>
>> Don't clobber status after reset_link() to restore the intended flow in
>> pcie_do_recovery().
>>
>> Fix the original problem by saving the return value from reset_link()
>> and use it later on to decide whether error recovery should be deemed
>> successful in the scenarios where the initial error status is
>> PCI_ERS_RESULT_{DISCONNECT,NO_AER_DRIVER}.
>
>I would rather rephrase the above to make it clear what is being proposed.
>Since the description seems to talk about the old problem and new solution
>all mixed up.

OK; will do that to clarify that what's being proposed here is:

     1. fix the regression introduced by commit 6d2c89441571
     2. address the problem that commit 6d2c89441571 aimed to fix

>> Fixes: 6d2c89441571 ("PCI/ERR: Update error status after reset_link()")
>> Signed-off-by: Hedi Berriche <hedi.berriche@hpe.com>
>> Cc: Russ Anderson <rja@hpe.com>
>> Cc: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
>> Cc: Bjorn Helgaas <bhelgaas@google.com>
>> Cc: Ashok Raj <ashok.raj@intel.com>
>> Cc: Keith Busch <keith.busch@intel.com>
>> Cc: Joerg Roedel <jroedel@suse.com>
>>
>> Cc: stable@kernel.org # v5.7+
>> ---
>>  drivers/pci/pcie/err.c | 13 ++++++++++---
>>  1 file changed, 10 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
>> index c543f419d8f9..dbd0b56bd6c1 100644
>> --- a/drivers/pci/pcie/err.c
>> +++ b/drivers/pci/pcie/err.c
>> @@ -150,7 +150,7 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
>>  			pci_channel_state_t state,
>>  			pci_ers_result_t (*reset_link)(struct pci_dev *pdev))
>>  {
>> -	pci_ers_result_t status = PCI_ERS_RESULT_CAN_RECOVER;
>> +	pci_ers_result_t post_reset_status, status = PCI_ERS_RESULT_CAN_RECOVER;
>
>why call it post_reset_status?

Perhaps post_reset_status is not a great choice; would reset_result or reset_link_result be better?

Cheers,
Hedi.

>
>>  	struct pci_bus *bus;
>>
>>  	/*
>> @@ -165,8 +165,8 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
>>  	pci_dbg(dev, "broadcast error_detected message\n");
>>  	if (state == pci_channel_io_frozen) {
>>  		pci_walk_bus(bus, report_frozen_detected, &status);
>> -		status = reset_link(dev);
>> -		if (status != PCI_ERS_RESULT_RECOVERED) {
>> +		post_reset_status = reset_link(dev);
>> +		if (post_reset_status != PCI_ERS_RESULT_RECOVERED) {
>>  			pci_warn(dev, "link reset failed\n");
>>  			goto failed;
>>  		}
>> @@ -174,6 +174,13 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
>>  		pci_walk_bus(bus, report_normal_detected, &status);
>>  	}
>>
>> +	if ((status == PCI_ERS_RESULT_DISCONNECT ||
>> +	     status == PCI_ERS_RESULT_NO_AER_DRIVER) &&
>> +	     post_reset_status == PCI_ERS_RESULT_RECOVERED) {
>> +		/* error recovery succeeded thanks to reset_link() */
>> +		status = PCI_ERS_RESULT_RECOVERED;
>> +	}
>> +
>>  	if (status == PCI_ERS_RESULT_CAN_RECOVER) {
>>  		status = PCI_ERS_RESULT_RECOVERED;
>>  		pci_dbg(dev, "broadcast mmio_enabled message\n");
>> --
>> 2.28.0
>>
Hedi Berriche Oct. 9, 2020, 4:11 a.m. UTC | #3
On Fri, Oct 09, 2020 at 05:09 Hedi Berriche wrote:
>On Fri, Oct 09, 2020 at 04:46 Raj, Ashok wrote:
>
>Hi Ashok,
>
>Thanks for looking into this.
>
>>On Fri, Oct 09, 2020 at 03:52:51AM +0100, Hedi Berriche wrote:
>>>Commit 6d2c89441571 ("PCI/ERR: Update error status after reset_link()")
>>>changed pcie_do_recovery() so that status is updated with the return
>>>value from reset_link(); this was to fix the problem where we would
>>>wrongly report recovery failure, despite a successful reset_link(),
>>>whenever the initial error status is PCI_ERS_RESULT_DISCONNECT or
>>>PCI_ERS_RESULT_NO_AER_DRIVER.
>>>
>>>Unfortunately this breaks the flow of pcie_do_recovery() as it prevents
>>
>>What is the reference to "this breaks" above?
>
>The code change introduced by commit 6d2c89441571; would
>
>    "this code change" instead of "this breaks"
>
>work better? If not, I can also rephrase the whole paragraph along the following lines:
>
>Commit 6d2c89441571 ("PCI/ERR: Update error status after reset_link()") breaks the flow
>of pcie_do_recovery() as it prevents the actions needed when the initial error is
>PCI_ERS_RESULT_CAN_RECOVER or PCI_ERS_RESULT_NEED_RESET from taking place which causes
>error recovery to fail.
>
>... and do away with the first paragraph.
>
>>>the actions needed when the initial error is PCI_ERS_RESULT_CAN_RECOVER
>>>or PCI_ERS_RESULT_NEED_RESET from taking place which causes error
>>>recovery to fail.
>>>
>>>Don't clobber status after reset_link() to restore the intended flow in
>>>pcie_do_recovery().
>>>
>>>Fix the original problem by saving the return value from reset_link()
>>>and use it later on to decide whether error recovery should be deemed
>>>successful in the scenarios where the initial error status is
>>>PCI_ERS_RESULT_{DISCONNECT,NO_AER_DRIVER}.
>>
>>I would rather rephrase the above to make it clear what is being proposed.
>>Since the description seems to talk about the old problem and new solution
>>all mixed up.
>
>OK; will do that to clarify that what's being proposed here is:
>
>    1. fix the regression introduced by commit 6d2c89441571
>    2. address the problem that commit 6d2c89441571 aimed to fix
>
>>>Fixes: 6d2c89441571 ("PCI/ERR: Update error status after reset_link()")
>>>Signed-off-by: Hedi Berriche <hedi.berriche@hpe.com>
>>>Cc: Russ Anderson <rja@hpe.com>
>>>Cc: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
>>>Cc: Bjorn Helgaas <bhelgaas@google.com>
>>>Cc: Ashok Raj <ashok.raj@intel.com>
>>>Cc: Keith Busch <keith.busch@intel.com>
>>>Cc: Joerg Roedel <jroedel@suse.com>
>>>
>>>Cc: stable@kernel.org # v5.7+
>>>---
>>> drivers/pci/pcie/err.c | 13 ++++++++++---
>>> 1 file changed, 10 insertions(+), 3 deletions(-)
>>>
>>>diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
>>>index c543f419d8f9..dbd0b56bd6c1 100644
>>>--- a/drivers/pci/pcie/err.c
>>>+++ b/drivers/pci/pcie/err.c
>>>@@ -150,7 +150,7 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
>>> 			pci_channel_state_t state,
>>> 			pci_ers_result_t (*reset_link)(struct pci_dev *pdev))
>>> {
>>>-	pci_ers_result_t status = PCI_ERS_RESULT_CAN_RECOVER;
>>>+	pci_ers_result_t post_reset_status, status = PCI_ERS_RESULT_CAN_RECOVER;
>>
>>why call it post_reset_status?
>
>Perhaps post_reset_status is not a great choice; would reset_result or reset_link_result be better?

... or just do this with a boolean instead as I had it in an earlier iteration of the patch before I
eventually opted to use an pci_ers_result_t.

Cheers,
Hedi.
>
>Cheers,
>Hedi.
>
>>
>>> 	struct pci_bus *bus;
>>>
>>> 	/*
>>>@@ -165,8 +165,8 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
>>> 	pci_dbg(dev, "broadcast error_detected message\n");
>>> 	if (state == pci_channel_io_frozen) {
>>> 		pci_walk_bus(bus, report_frozen_detected, &status);
>>>-		status = reset_link(dev);
>>>-		if (status != PCI_ERS_RESULT_RECOVERED) {
>>>+		post_reset_status = reset_link(dev);
>>>+		if (post_reset_status != PCI_ERS_RESULT_RECOVERED) {
>>> 			pci_warn(dev, "link reset failed\n");
>>> 			goto failed;
>>> 		}
>>>@@ -174,6 +174,13 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
>>> 		pci_walk_bus(bus, report_normal_detected, &status);
>>> 	}
>>>
>>>+	if ((status == PCI_ERS_RESULT_DISCONNECT ||
>>>+	     status == PCI_ERS_RESULT_NO_AER_DRIVER) &&
>>>+	     post_reset_status == PCI_ERS_RESULT_RECOVERED) {
>>>+		/* error recovery succeeded thanks to reset_link() */
>>>+		status = PCI_ERS_RESULT_RECOVERED;
>>>+	}
>>>+
>>> 	if (status == PCI_ERS_RESULT_CAN_RECOVER) {
>>> 		status = PCI_ERS_RESULT_RECOVERED;
>>> 		pci_dbg(dev, "broadcast mmio_enabled message\n");
>>>--
>>>2.28.0
>>>
>
>-- 
>Be careful of reading health books, you might die of a misprint.
>	-- Mark Twain
diff mbox series

Patch

diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
index c543f419d8f9..dbd0b56bd6c1 100644
--- a/drivers/pci/pcie/err.c
+++ b/drivers/pci/pcie/err.c
@@ -150,7 +150,7 @@  pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
 			pci_channel_state_t state,
 			pci_ers_result_t (*reset_link)(struct pci_dev *pdev))
 {
-	pci_ers_result_t status = PCI_ERS_RESULT_CAN_RECOVER;
+	pci_ers_result_t post_reset_status, status = PCI_ERS_RESULT_CAN_RECOVER;
 	struct pci_bus *bus;
 
 	/*
@@ -165,8 +165,8 @@  pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
 	pci_dbg(dev, "broadcast error_detected message\n");
 	if (state == pci_channel_io_frozen) {
 		pci_walk_bus(bus, report_frozen_detected, &status);
-		status = reset_link(dev);
-		if (status != PCI_ERS_RESULT_RECOVERED) {
+		post_reset_status = reset_link(dev);
+		if (post_reset_status != PCI_ERS_RESULT_RECOVERED) {
 			pci_warn(dev, "link reset failed\n");
 			goto failed;
 		}
@@ -174,6 +174,13 @@  pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
 		pci_walk_bus(bus, report_normal_detected, &status);
 	}
 
+	if ((status == PCI_ERS_RESULT_DISCONNECT ||
+	     status == PCI_ERS_RESULT_NO_AER_DRIVER) &&
+	     post_reset_status == PCI_ERS_RESULT_RECOVERED) {
+		/* error recovery succeeded thanks to reset_link() */
+		status = PCI_ERS_RESULT_RECOVERED;
+	}
+
 	if (status == PCI_ERS_RESULT_CAN_RECOVER) {
 		status = PCI_ERS_RESULT_RECOVERED;
 		pci_dbg(dev, "broadcast mmio_enabled message\n");