From: Eric Pilmore epilmore@gigaio.com
[ Upstream commit 95e5fda3b5f9ed8239b145da3fa01e641cf5d53c ]
The interrupt handler (pt_core_irq_handler()) of the ptdma driver can be called from interrupt context. The code flow in this function can lead down to pt_core_execute_cmd() which will attempt to grab a mutex, which is not appropriate in interrupt context and ultimately leads to a kernel panic. The fix here changes this mutex to a spinlock, which has been verified to resolve the issue.
Fixes: fa5d823b16a9 ("dmaengine: ptdma: Initial driver for the AMD PTDMA") Signed-off-by: Eric Pilmore epilmore@gigaio.com Link: https://lore.kernel.org/r/20230119033907.35071-1-epilmore@gigaio.com Signed-off-by: Vinod Koul vkoul@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/dma/ptdma/ptdma-dev.c | 7 ++++--- drivers/dma/ptdma/ptdma.h | 2 +- 2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/dma/ptdma/ptdma-dev.c b/drivers/dma/ptdma/ptdma-dev.c index daafea5bc35d..bca4063b0dce 100644 --- a/drivers/dma/ptdma/ptdma-dev.c +++ b/drivers/dma/ptdma/ptdma-dev.c @@ -71,12 +71,13 @@ static int pt_core_execute_cmd(struct ptdma_desc *desc, struct pt_cmd_queue *cmd bool soc = FIELD_GET(DWORD0_SOC, desc->dw0); u8 *q_desc = (u8 *)&cmd_q->qbase[cmd_q->qidx]; u32 tail; + unsigned long flags;
if (soc) { desc->dw0 |= FIELD_PREP(DWORD0_IOC, desc->dw0); desc->dw0 &= ~DWORD0_SOC; } - mutex_lock(&cmd_q->q_mutex); + spin_lock_irqsave(&cmd_q->q_lock, flags);
/* Copy 32-byte command descriptor to hw queue. */ memcpy(q_desc, desc, 32); @@ -91,7 +92,7 @@ static int pt_core_execute_cmd(struct ptdma_desc *desc, struct pt_cmd_queue *cmd
/* Turn the queue back on using our cached control register */ pt_start_queue(cmd_q); - mutex_unlock(&cmd_q->q_mutex); + spin_unlock_irqrestore(&cmd_q->q_lock, flags);
return 0; } @@ -197,7 +198,7 @@ int pt_core_init(struct pt_device *pt)
cmd_q->pt = pt; cmd_q->dma_pool = dma_pool; - mutex_init(&cmd_q->q_mutex); + spin_lock_init(&cmd_q->q_lock);
/* Page alignment satisfies our needs for N <= 128 */ cmd_q->qsize = Q_SIZE(Q_DESC_SIZE); diff --git a/drivers/dma/ptdma/ptdma.h b/drivers/dma/ptdma/ptdma.h index afbf192c9230..0f0b400a864e 100644 --- a/drivers/dma/ptdma/ptdma.h +++ b/drivers/dma/ptdma/ptdma.h @@ -196,7 +196,7 @@ struct pt_cmd_queue { struct ptdma_desc *qbase;
/* Aligned queue start address (per requirement) */ - struct mutex q_mutex ____cacheline_aligned; + spinlock_t q_lock ____cacheline_aligned; unsigned int qidx;
unsigned int qsize;