From: Ranjan Kumar Date: Thu, 6 Apr 2023 10:18:19 +0000 (+0530) Subject: scsi: mpi3mr: Use IRQ save variants of spinlock to protect chain frame allocation X-Git-Tag: v6.4-rc1~133^2~4 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2acc635a0e5e91c267f2cb1c25748e8d06888e63;p=thirdparty%2Fkernel%2Flinux.git 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: Ranjan Kumar Link: https://lore.kernel.org/r/20230406101819.10109-1-ranjan.kumar@broadcom.com Signed-off-by: Martin K. Petersen --- diff --git a/drivers/scsi/mpi3mr/mpi3mr_os.c b/drivers/scsi/mpi3mr/mpi3mr_os.c index 5c2fd09b94974..d627355303d79 100644 --- a/drivers/scsi/mpi3mr/mpi3mr_os.c +++ b/drivers/scsi/mpi3mr/mpi3mr_os.c @@ -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; }