Commit 2acc635a authored by Ranjan Kumar's avatar Ranjan Kumar Committed by Martin K. Petersen
Browse files

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



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: default avatarRanjan Kumar <ranjan.kumar@broadcom.com>
Link: https://lore.kernel.org/r/20230406101819.10109-1-ranjan.kumar@broadcom.com


Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent b32283d7

drivers/scsi/mpi3mr/mpi3mr_os.c

+3 −3
Original line number Diff line number Diff line
@@ -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;

}