Re: [PATCH v5 2/7] scsi: libsas: shut down the PHY if events reached the threshold

[Hannes Reinecke]

On 12/15/2017 01:18 PM, Hannes Reinecke wrote:
> On 12/08/2017 10:42 AM, Jason Yan wrote:
>> If the PHY burst too many events, we will alloc a lot of events for the
>> worker. This may leads to memory exhaustion.
>>
>> Dan Williams suggested to shut down the PHY if the events reached the
>> threshold, because in this case the PHY may have gone into some
>> erroneous state. Users can re-enable the PHY by sysfs if they want.
>>
>> We cannot use the fixed memory pool because if we run out of events, the
>> shut down event and loss of signal event will lost too. The events still
>> need to be allocated and processed in this case.
>>
>> Suggested-by: Dan Williams <dan.j.williams@xxxxxxxxx>
>> Signed-off-by: Jason Yan <yanaijie@xxxxxxxxxx>
>> CC: John Garry <john.garry@xxxxxxxxxx>
>> CC: Johannes Thumshirn <jthumshirn@xxxxxxx>
>> CC: Ewan Milne <emilne@xxxxxxxxxx>
>> CC: Christoph Hellwig <hch@xxxxxx>
>> CC: Tomas Henzl <thenzl@xxxxxxxxxx>
>> ---
>>  drivers/scsi/libsas/sas_init.c | 33 ++++++++++++++++++++++++++++++++-
>>  drivers/scsi/libsas/sas_phy.c  | 27 ++++++++++++++++++++++++++-
>>  include/scsi/libsas.h          |  6 ++++++
>>  3 files changed, 64 insertions(+), 2 deletions(-)
>>
> Well, this still looks a bit error prone; what if the system runs out of
> memory before the pool is exhausted?
> (Also a threshold of 1024 events is a bit arbitrary; one might want to
> adjust that).
> 
> Couldn't you allocate two static events always (for shutdown and signal
> loss), and then use a fixed pool?
> 
Has actually been resolved by the next patch.

Reviewed-by: Hannes Reinecke <hare@xxxxxxxx>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
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