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scsi: mpi3mr: Use IRQ save variants of spinlock to protect chain frame allocation

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Driver uses spin lock without irqsave when it needs to acquire a chain
frame. This is done to protect chain frame allocation from multiple
submission threads. If there is any I/O queued from an interrupt context,
and if that requires a chain frame, and if the chain lock is held by the CPU
which got interrupted, then there will be a possible deadlock.

Signed-off-by: Ranjan Kumar <ranjan.kumar@broadcom.com>
Link: https://lore.kernel.org/r/20230406101819.10109-1-ranjan.kumar@broadcom.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Ranjan Kumar 2023-04-06 15:48:19 +05:30 committed by Martin K. Petersen
parent b32283d753
commit 2acc635a0e
1 changed files with 3 additions and 3 deletions
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6
drivers/scsi/mpi3mr/mpi3mr_os.c
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@ -3331,19 +3331,19 @@ static int mpi3mr_get_chain_idx(struct mpi3mr_ioc *mrioc)
{
u8 retry_count = 5;
int cmd_idx = -1;
unsigned long flags;
spin_lock_irqsave(&mrioc->chain_buf_lock, flags);
do {
spin_lock(&mrioc->chain_buf_lock);
cmd_idx = find_first_zero_bit(mrioc->chain_bitmap,
mrioc->chain_buf_count);
if (cmd_idx < mrioc->chain_buf_count) {
set_bit(cmd_idx, mrioc->chain_bitmap);
spin_unlock(&mrioc->chain_buf_lock);
break;
}
spin_unlock(&mrioc->chain_buf_lock);
cmd_idx = -1;
} while (retry_count--);
spin_unlock_irqrestore(&mrioc->chain_buf_lock, flags);
return cmd_idx;
}