ptdma: pt_core_execute_cmd() should use spinlock

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>

diff --git a/drivers/dma/ptdma/ptdma-dev.c b/drivers/dma/ptdma/ptdma-dev.c
index 377da23012ac23e826234673c1095f8dc70aefa3..a2bf13ff18b6d2904b489f880c54563c8e12410d 100644 (file)
--- 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;
 }
@@ -199,7 +200,7 @@ 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 d093c43b7d1343b11227e14b815149085a32696f..21b4bf895200b5512ca91a54a19e2ce93623d46e 100644 (file)
--- 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;