HI Tomas, This lock is not needed as we are already protecting the tag allocation and freeing with the pm8001_ha->lock. We are always acquiring this lock before calling pm8001_tag_alloc().
We are allocating and freeing the tag in following paths, 1) Request/Response path : This we are protecting using pm8001_ha->lock. 2)Driver initialization : We are not using the lock here . As there only one will be running, we don't need a lock here. So there is no need of a specific lock for tag allocation. Regards, Viswas G -----Original Message----- From: Tomas Henzl [mailto:the...@redhat.com] Sent: Thursday, June 26, 2014 8:48 PM To: linux-scsi@vger.kernel.org Cc: zzzAnand Kumar Santhanam(Nov-20-2013); Vasanthalakshmi Tharmarajan; Suresh Thiagarajan; Viswas G; Tomas Henzl Subject: [PATCH 3/4] pm8001: add a new spinlock to protect the CCB Patch adds a new spinlock to protect the ccb management. It may happen that concurrent threads become the same tag value from the 'alloc' function', the spinlock prevents this situation. Signed-off-by: Tomas Henzl <the...@redhat.com> --- drivers/scsi/pm8001/pm8001_init.c | 1 + drivers/scsi/pm8001/pm8001_sas.c | 7 ++++++- drivers/scsi/pm8001/pm8001_sas.h | 1 + 3 files changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/pm8001/pm8001_init.c b/drivers/scsi/pm8001/pm8001_init.c index c4f31b21..56b61e5 100644 --- a/drivers/scsi/pm8001/pm8001_init.c +++ b/drivers/scsi/pm8001/pm8001_init.c @@ -246,6 +246,7 @@ static int pm8001_alloc(struct pm8001_hba_info *pm8001_ha, { int i; spin_lock_init(&pm8001_ha->lock); + spin_lock_init(&pm8001_ha->bitmap_lock); PM8001_INIT_DBG(pm8001_ha, pm8001_printk("pm8001_alloc: PHY:%x\n", pm8001_ha->chip->n_phy)); diff --git a/drivers/scsi/pm8001/pm8001_sas.c b/drivers/scsi/pm8001/pm8001_sas.c index be55859..34cea82 100644 --- a/drivers/scsi/pm8001/pm8001_sas.c +++ b/drivers/scsi/pm8001/pm8001_sas.c @@ -77,11 +77,16 @@ inline int pm8001_tag_alloc(struct pm8001_hba_info *pm8001_ha, u32 *tag_out) { unsigned int tag; void *bitmap = pm8001_ha->tags; + unsigned long flags; + spin_lock_irqsave(&pm8001_ha->bitmap_lock, flags); tag = find_first_zero_bit(bitmap, pm8001_ha->tags_num); - if (tag >= pm8001_ha->tags_num) + if (tag >= pm8001_ha->tags_num) { + spin_unlock_irqrestore(&pm8001_ha->bitmap_lock, flags); return -SAS_QUEUE_FULL; + } set_bit(tag, bitmap); + spin_unlock_irqrestore(&pm8001_ha->bitmap_lock, flags); *tag_out = tag; return 0; } diff --git a/drivers/scsi/pm8001/pm8001_sas.h b/drivers/scsi/pm8001/pm8001_sas.h index 14106ad..f6b2ac5 100644 --- a/drivers/scsi/pm8001/pm8001_sas.h +++ b/drivers/scsi/pm8001/pm8001_sas.h @@ -475,6 +475,7 @@ struct pm8001_hba_info { struct list_head list; unsigned long flags; spinlock_t lock;/* host-wide lock */ + spinlock_t bitmap_lock; struct pci_dev *pdev;/* our device */ struct device *dev; struct pm8001_hba_memspace io_mem[6]; -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
