Re: [PATCH] scsi: sd_zbc: update write pointer offset cache

[Damien Le Moal <Damien.LeMoal@wdc.com>]

On 2021/03/10 18:48, Johannes Thumshirn wrote:
> Recent changes changed the completion of SCSI commands from Soft-IRQ
> context to IRQ context. This triggers the following warning, when we're
> completing writes to zoned block devices that go through the zone append
> emulation:
> 
>  CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.12.0-rc2+ #2
>  Hardware name: Supermicro Super Server/X10SRL-F, BIOS 2.0 12/17/2015
>  RIP: 0010:__local_bh_disable_ip+0x3f/0x50
>  RSP: 0018:ffff8883e1409ba8 EFLAGS: 00010006
>  RAX: 0000000080010001 RBX: 0000000000000001 RCX: 0000000000000013
>  RDX: ffff888129e4d200 RSI: 0000000000000201 RDI: ffffffff915b9dbd
>  RBP: ffff888113e9a540 R08: ffff888113e9a540 R09: 00000000000077f0
>  R10: 0000000000080000 R11: 0000000000000001 R12: ffff888129e4d200
>  R13: 0000000000001000 R14: 00000000000077f0 R15: ffff888129e4d218
>  FS:  0000000000000000(0000) GS:ffff8883e1400000(0000) knlGS:0000000000000000
>  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>  CR2: 00007f2f8418ebc0 CR3: 000000021202a006 CR4: 00000000001706f0
>  Call Trace:
>   <IRQ>
>   _raw_spin_lock_bh+0x18/0x40
>   sd_zbc_complete+0x43d/0x1150
>   sd_done+0x631/0x1040
>   ? mark_lock+0xe4/0x2fd0
>   ? provisioning_mode_store+0x3f0/0x3f0
>   scsi_finish_command+0x31b/0x5c0
>   _scsih_io_done+0x960/0x29e0 [mpt3sas]
>   ? mpt3sas_scsih_scsi_lookup_get+0x1c7/0x340 [mpt3sas]
>   ? __lock_acquire+0x166b/0x58b0
>   ? _get_st_from_smid+0x4a/0x80 [mpt3sas]
>   _base_process_reply_queue+0x23f/0x26e0 [mpt3sas]
>   ? lock_is_held_type+0x98/0x110
>   ? find_held_lock+0x2c/0x110
>   ? mpt3sas_base_sync_reply_irqs+0x360/0x360 [mpt3sas]
>   _base_interrupt+0x8d/0xd0 [mpt3sas]
>   ? rcu_read_lock_sched_held+0x3f/0x70
>   __handle_irq_event_percpu+0x24d/0x600
>   handle_irq_event+0xef/0x240
>   ? handle_irq_event_percpu+0x110/0x110
>   handle_edge_irq+0x1f6/0xb60
>   __common_interrupt+0x75/0x160
>   common_interrupt+0x7b/0xa0
>   </IRQ>
>   asm_common_interrupt+0x1e/0x40
> 
> Don't use spin_lock_bh() to protect the update of the write pointer offset
> cache, but use spin_lock_irqsave() for it.
> 
> Reported-by: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> ---
>  drivers/scsi/sd_zbc.c | 19 +++++++++++--------
>  1 file changed, 11 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/scsi/sd_zbc.c b/drivers/scsi/sd_zbc.c
> index ee558675eab4..994f1b8e3504 100644
> --- a/drivers/scsi/sd_zbc.c
> +++ b/drivers/scsi/sd_zbc.c
> @@ -280,27 +280,28 @@ static int sd_zbc_update_wp_offset_cb(struct blk_zone *zone, unsigned int idx,
>  static void sd_zbc_update_wp_offset_workfn(struct work_struct *work)
>  {
>  	struct scsi_disk *sdkp;
> +	unsigned long flags;
>  	unsigned int zno;
>  	int ret;
>  
>  	sdkp = container_of(work, struct scsi_disk, zone_wp_offset_work);
>  
> -	spin_lock_bh(&sdkp->zones_wp_offset_lock);
> +	spin_lock_irqsave(&sdkp->zones_wp_offset_lock, flags);
>  	for (zno = 0; zno < sdkp->nr_zones; zno++) {
>  		if (sdkp->zones_wp_offset[zno] != SD_ZBC_UPDATING_WP_OFST)
>  			continue;
>  
> -		spin_unlock_bh(&sdkp->zones_wp_offset_lock);
> +		spin_unlock_irqrestore(&sdkp->zones_wp_offset_lock, flags);
>  		ret = sd_zbc_do_report_zones(sdkp, sdkp->zone_wp_update_buf,
>  					     SD_BUF_SIZE,
>  					     zno * sdkp->zone_blocks, true);
> -		spin_lock_bh(&sdkp->zones_wp_offset_lock);
> +		spin_lock_irqsave(&sdkp->zones_wp_offset_lock, flags);
>  		if (!ret)
>  			sd_zbc_parse_report(sdkp, sdkp->zone_wp_update_buf + 64,
>  					    zno, sd_zbc_update_wp_offset_cb,
>  					    sdkp);
>  	}
> -	spin_unlock_bh(&sdkp->zones_wp_offset_lock);
> +	spin_unlock_irqrestore(&sdkp->zones_wp_offset_lock, flags);
>  
>  	scsi_device_put(sdkp->device);
>  }
> @@ -324,6 +325,7 @@ blk_status_t sd_zbc_prepare_zone_append(struct scsi_cmnd *cmd, sector_t *lba,
>  	struct request *rq = cmd->request;
>  	struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
>  	unsigned int wp_offset, zno = blk_rq_zone_no(rq);
> +	unsigned long flags;
>  	blk_status_t ret;
>  
>  	ret = sd_zbc_cmnd_checks(cmd);
> @@ -337,7 +339,7 @@ blk_status_t sd_zbc_prepare_zone_append(struct scsi_cmnd *cmd, sector_t *lba,
>  	if (!blk_req_zone_write_trylock(rq))
>  		return BLK_STS_ZONE_RESOURCE;
>  
> -	spin_lock_bh(&sdkp->zones_wp_offset_lock);
> +	spin_lock_irqsave(&sdkp->zones_wp_offset_lock, flags);
>  	wp_offset = sdkp->zones_wp_offset[zno];
>  	switch (wp_offset) {
>  	case SD_ZBC_INVALID_WP_OFST:
> @@ -366,7 +368,7 @@ blk_status_t sd_zbc_prepare_zone_append(struct scsi_cmnd *cmd, sector_t *lba,
>  
>  		*lba += wp_offset;
>  	}
> -	spin_unlock_bh(&sdkp->zones_wp_offset_lock);
> +	spin_unlock_irqrestore(&sdkp->zones_wp_offset_lock, flags);
>  	if (ret)
>  		blk_req_zone_write_unlock(rq);
>  	return ret;
> @@ -445,6 +447,7 @@ static unsigned int sd_zbc_zone_wp_update(struct scsi_cmnd *cmd,
>  	struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
>  	unsigned int zno = blk_rq_zone_no(rq);
>  	enum req_opf op = req_op(rq);
> +	unsigned long flags;
>  
>  	/*
>  	 * If we got an error for a command that needs updating the write
> @@ -452,7 +455,7 @@ static unsigned int sd_zbc_zone_wp_update(struct scsi_cmnd *cmd,
>  	 * invalid to force an update from disk the next time a zone append
>  	 * command is issued.
>  	 */
> -	spin_lock_bh(&sdkp->zones_wp_offset_lock);
> +	spin_lock_irqsave(&sdkp->zones_wp_offset_lock, flags);
>  
>  	if (result && op != REQ_OP_ZONE_RESET_ALL) {
>  		if (op == REQ_OP_ZONE_APPEND) {
> @@ -496,7 +499,7 @@ static unsigned int sd_zbc_zone_wp_update(struct scsi_cmnd *cmd,
>  	}
>  
>  unlock_wp_offset:
> -	spin_unlock_bh(&sdkp->zones_wp_offset_lock);
> +	spin_unlock_irqrestore(&sdkp->zones_wp_offset_lock, flags);
>  
>  	return good_bytes;
>  }
> 

Looks good to me.

Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>

-- 
Damien Le Moal
Western Digital Research