From: John Garry <john.garry@huawei.com>
To: Hannes Reinecke <hare@suse.de>, <don.brace@microsemi.com>,
<hare@suse.com>
Cc: <axboe@kernel.dk>, <jejb@linux.ibm.com>,
<martin.petersen@oracle.com>, <kashyap.desai@broadcom.com>,
<sumit.saxena@broadcom.com>, <ming.lei@redhat.com>,
<bvanassche@acm.org>, <hch@lst.de>,
<shivasharan.srikanteshwara@broadcom.com>,
<linux-block@vger.kernel.org>, <linux-scsi@vger.kernel.org>,
<esc.storagedev@microsemi.com>, <chenxiang66@hisilicon.com>,
<megaraidlinux.pdl@broadcom.com>
Subject: Re: [PATCH RFC v7 11/12] smartpqi: enable host tagset
Date: Tue, 18 Aug 2020 09:33:28 +0100 [thread overview]
Message-ID: <7c535e7f-9c32-3d53-cdcc-408e8faee46c@huawei.com> (raw)
In-Reply-To: <f4425d8b-d132-c5c7-c854-2be948795bda@suse.de>
On 14/07/2020 15:02, Hannes Reinecke wrote:
> On 7/14/20 3:16 PM, John Garry wrote:
>> Hi Hannes,
>>
>>> static struct pqi_io_request *pqi_alloc_io_request(
>>> - struct pqi_ctrl_info *ctrl_info)
>>> + struct pqi_ctrl_info *ctrl_info, struct scsi_cmnd *scmd)
>>> {
>>> struct pqi_io_request *io_request;
>>> + unsigned int limit = PQI_RESERVED_IO_SLOTS;
>>> u16 i = ctrl_info->next_io_request_slot; /* benignly racy */
>>> - while (1) {
>>> + if (scmd) {
>>> + u32 blk_tag = blk_mq_unique_tag(scmd->request);
>>> +
>>> + i = blk_mq_unique_tag_to_tag(blk_tag) + limit;
>>> io_request = &ctrl_info->io_request_pool[i];
>>
>> This looks ok
>>
>>> - if (atomic_inc_return(&io_request->refcount) == 1)
>>> - break;
>>> - atomic_dec(&io_request->refcount);
>>> - i = (i + 1) % ctrl_info->max_io_slots;
>>> + if (WARN_ON(atomic_inc_return(&io_request->refcount) > 1)) {
>>> + atomic_dec(&io_request->refcount);
>>> + return NULL;
>>> + }
>>> + } else {
>>> + while (1) {
>>> + io_request = &ctrl_info->io_request_pool[i];
>>> + if (atomic_inc_return(&io_request->refcount) == 1)
>>> + break;
>>> + atomic_dec(&io_request->refcount);
>>> + i = (i + 1) % limit;
>>
>> To me, the range we use here looks incorrect. I would assume we should
>> restrict range to [max_io_slots - PQI_RESERVED_IO_SLOTS, max_io_slots).
>>
>> But then your reserved commands support would solve that.
>>
> This branch of the 'if' condition will only be taken for internal
> commands, for which we only allow up to PQI_RESERVED_IO_SLOTS.
> And we set the 'normal' I/O commands above at an offset, so we're fine here.
Here is the code:
----8<----
unsigned int limit = PQI_RESERVED_IO_SLOTS;
u16 i = ctrl_info->next_io_request_slot; /* benignly racy */
if (scmd) {
u32 blk_tag = blk_mq_unique_tag(scmd->request);
i = blk_mq_unique_tag_to_tag(blk_tag) + limit;
io_request = &ctrl_info->io_request_pool[i];
if (WARN_ON(atomic_inc_return(&io_request->refcount) > 1)) {
atomic_dec(&io_request->refcount);
return NULL;
}
} else {
while (1) {
io_request = &ctrl_info->io_request_pool[i];
if (atomic_inc_return(&io_request->refcount) == 1)
break;
atomic_dec(&io_request->refcount);
i = (i + 1) % limit;
}
}
/* benignly racy */
ctrl_info->next_io_request_slot = (i + 1) % ctrl_info->max_io_slots;
---->8----
Is how we set ctrl_info->next_io_request_slot ok? Should it be:
ctrl_info->next_io_request_slot = (i + 1) % limit;
And also moved into 'else' leg for good measure.
Thanks,
John
next prev parent reply other threads:[~2020-08-18 8:35 UTC|newest]
Thread overview: 123+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-10 17:29 [PATCH RFC v7 00/12] blk-mq/scsi: Provide hostwide shared tags for SCSI HBAs John Garry
2020-06-10 17:29 ` [PATCH RFC v7 01/12] blk-mq: rename BLK_MQ_F_TAG_SHARED as BLK_MQ_F_TAG_QUEUE_SHARED John Garry
2020-06-10 17:29 ` [PATCH RFC v7 02/12] blk-mq: rename blk_mq_update_tag_set_depth() John Garry
2020-06-11 2:57 ` Ming Lei
2020-06-11 8:26 ` John Garry
2020-06-23 11:25 ` John Garry
2020-06-23 14:23 ` Hannes Reinecke
2020-06-24 8:13 ` Kashyap Desai
2020-06-29 16:18 ` John Garry
2020-08-10 16:51 ` Kashyap Desai
2020-08-11 8:01 ` John Garry
2020-08-11 16:34 ` Kashyap Desai
2020-06-10 17:29 ` [PATCH RFC v7 03/12] blk-mq: Use pointers for blk_mq_tags bitmap tags John Garry
2020-06-10 17:29 ` [PATCH RFC v7 04/12] blk-mq: Facilitate a shared sbitmap per tagset John Garry
2020-06-11 3:37 ` Ming Lei
2020-06-11 10:09 ` John Garry
2020-06-10 17:29 ` [PATCH RFC v7 05/12] blk-mq: Record nr_active_requests per queue for when using shared sbitmap John Garry
2020-06-11 4:04 ` Ming Lei
2020-06-11 10:22 ` John Garry
2020-06-10 17:29 ` [PATCH RFC v7 06/12] blk-mq: Record active_queues_shared_sbitmap per tag_set " John Garry
2020-06-11 13:16 ` Hannes Reinecke
2020-06-11 14:22 ` John Garry
2020-06-10 17:29 ` [PATCH RFC v7 07/12] blk-mq: Add support in hctx_tags_bitmap_show() for a " John Garry
2020-06-11 13:19 ` Hannes Reinecke
2020-06-11 14:33 ` John Garry
2020-06-12 6:06 ` Hannes Reinecke
2020-06-29 15:32 ` About sbitmap_bitmap_show() and cleared bits (was Re: [PATCH RFC v7 07/12] blk-mq: Add support in hctx_tags_bitmap_show() for a shared sbitmap) John Garry
2020-06-30 6:33 ` Hannes Reinecke
2020-06-30 7:30 ` John Garry
2020-06-30 11:36 ` John Garry
2020-06-30 14:55 ` Bart Van Assche
2020-07-13 9:41 ` [PATCH RFC v7 07/12] blk-mq: Add support in hctx_tags_bitmap_show() for a shared sbitmap John Garry
2020-07-13 12:20 ` Hannes Reinecke
2020-06-10 17:29 ` [PATCH RFC v7 08/12] scsi: Add template flag 'host_tagset' John Garry
2020-06-10 17:29 ` [PATCH RFC v7 09/12] scsi: hisi_sas: Switch v3 hw to MQ John Garry
2020-06-10 17:29 ` [PATCH RFC v7 10/12] megaraid_sas: switch fusion adapters " John Garry
2020-07-02 10:23 ` Kashyap Desai
2020-07-06 8:23 ` John Garry
2020-07-06 8:45 ` Hannes Reinecke
2020-07-06 9:26 ` John Garry
2020-07-06 9:40 ` Hannes Reinecke
2020-07-06 19:19 ` Kashyap Desai
2020-07-07 7:58 ` John Garry
2020-07-07 14:45 ` Kashyap Desai
2020-07-07 16:17 ` John Garry
2020-07-09 19:01 ` Kashyap Desai
2020-07-10 8:10 ` John Garry
2020-07-13 7:55 ` Kashyap Desai
2020-07-13 8:42 ` John Garry
2020-07-19 19:07 ` Kashyap Desai
2020-07-20 7:23 ` Kashyap Desai
2020-07-20 9:18 ` John Garry
2020-07-21 1:13 ` Ming Lei
2020-07-21 6:53 ` Kashyap Desai
2020-07-22 4:12 ` Ming Lei
2020-07-22 5:30 ` Kashyap Desai
2020-07-22 8:04 ` Ming Lei
2020-07-22 9:32 ` John Garry
2020-07-23 14:07 ` Ming Lei
2020-07-23 17:29 ` John Garry
2020-07-24 2:47 ` Ming Lei
2020-07-28 7:54 ` John Garry
2020-07-28 8:45 ` Ming Lei
2020-07-29 5:25 ` Kashyap Desai
2020-07-29 15:36 ` Ming Lei
2020-07-29 18:31 ` Kashyap Desai
2020-08-04 8:36 ` Ming Lei
2020-08-04 9:27 ` Kashyap Desai
2020-08-05 8:40 ` Ming Lei
2020-08-06 10:25 ` Kashyap Desai
2020-08-06 13:38 ` Ming Lei
2020-08-06 14:37 ` Kashyap Desai
2020-08-06 15:29 ` Ming Lei
2020-08-08 19:05 ` Kashyap Desai
2020-08-09 2:16 ` Ming Lei
2020-08-10 16:38 ` Kashyap Desai
2020-08-11 8:09 ` John Garry
2020-08-04 17:00 ` John Garry
2020-08-05 2:56 ` Ming Lei
2020-07-28 8:01 ` Kashyap Desai
2020-07-08 11:31 ` John Garry
2020-06-10 17:29 ` [PATCH RFC v7 11/12] smartpqi: enable host tagset John Garry
2020-07-14 13:16 ` John Garry
2020-07-14 13:31 ` John Garry
2020-07-14 18:16 ` Don.Brace
2020-07-15 7:28 ` John Garry
2020-07-14 14:02 ` Hannes Reinecke
2020-08-18 8:33 ` John Garry [this message]
2020-06-10 17:29 ` [PATCH RFC v7 12/12] hpsa: enable host_tagset and switch to MQ John Garry
2020-07-14 7:37 ` John Garry
2020-07-14 7:41 ` Hannes Reinecke
2020-07-14 7:52 ` John Garry
2020-07-14 8:06 ` Ming Lei
2020-07-14 9:53 ` John Garry
2020-07-14 10:14 ` Ming Lei
2020-07-14 10:43 ` Hannes Reinecke
2020-07-14 10:19 ` Hannes Reinecke
2020-07-14 10:35 ` John Garry
2020-07-14 10:44 ` Ming Lei
2020-07-14 10:52 ` John Garry
2020-07-14 12:04 ` Ming Lei
2020-08-03 20:39 ` Don.Brace
2020-08-04 9:27 ` John Garry
2020-08-04 15:18 ` Don.Brace
2020-08-05 11:21 ` John Garry
2020-08-14 21:04 ` Don.Brace
2020-08-17 8:00 ` John Garry
2020-08-17 18:39 ` Don.Brace
2020-08-18 7:14 ` Hannes Reinecke
2020-07-16 16:14 ` Don.Brace
2020-07-16 19:45 ` Don.Brace
2020-07-17 10:11 ` John Garry
2020-06-11 3:07 ` [PATCH RFC v7 00/12] blk-mq/scsi: Provide hostwide shared tags for SCSI HBAs Ming Lei
2020-06-11 9:35 ` John Garry
2020-06-12 18:47 ` Kashyap Desai
2020-06-15 2:13 ` Ming Lei
2020-06-15 6:57 ` Kashyap Desai
2020-06-16 1:00 ` Ming Lei
2020-06-17 11:26 ` Kashyap Desai
2020-06-22 6:24 ` Hannes Reinecke
2020-06-23 0:55 ` Ming Lei
2020-06-23 11:50 ` Kashyap Desai
2020-06-23 12:11 ` Kashyap Desai
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