habanalabs: disable IRQ in user interrupts spinlock

Because this spinlock is taken in an interrupt handler, we must use
the spin_lock_irqsave/irqrestore version to disable the interrupts
on the local CPU. Otherwise, we can have a potential deadlock (if
the interrupt handler is scheduled to run on the same cpu that the
code who took the lock was running on).

Signed-off-by: Oded Gabbay <ogabbay@kernel.org>

diff --git a/drivers/misc/habanalabs/common/command_submission.c b/drivers/misc/habanalabs/common/command_submission.c
index 3a67265..8a2f75d 100644 (file)
--- a/drivers/misc/habanalabs/common/command_submission.c
+++ b/drivers/misc/habanalabs/common/command_submission.c
@@ -923,13 +923,14 @@ static void
 wake_pending_user_interrupt_threads(struct hl_user_interrupt *interrupt)
 {
        struct hl_user_pending_interrupt *pend;
+       unsigned long flags;
 
-       spin_lock(&interrupt->wait_list_lock);
+       spin_lock_irqsave(&interrupt->wait_list_lock, flags);
        list_for_each_entry(pend, &interrupt->wait_list_head, wait_list_node) {
                pend->fence.error = -EIO;
                complete_all(&pend->fence.completion);
        }
-       spin_unlock(&interrupt->wait_list_lock);
+       spin_unlock_irqrestore(&interrupt->wait_list_lock, flags);
 }
 
 void hl_release_pending_user_interrupts(struct hl_device *hdev)
@@ -2714,9 +2715,9 @@ static int _hl_interrupt_wait_ioctl(struct hl_device *hdev, struct hl_ctx *ctx,
 {
        struct hl_user_pending_interrupt *pend;
        struct hl_user_interrupt *interrupt;
-       unsigned long timeout;
-       long completion_rc;
+       unsigned long timeout, flags;
        u32 completion_value;
+       long completion_rc;
        int rc = 0;
 
        if (timeout_us == U32_MAX)
@@ -2739,7 +2740,7 @@ static int _hl_interrupt_wait_ioctl(struct hl_device *hdev, struct hl_ctx *ctx,
        else
                interrupt = &hdev->user_interrupt[interrupt_offset];
 
-       spin_lock(&interrupt->wait_list_lock);
+       spin_lock_irqsave(&interrupt->wait_list_lock, flags);
        if (!hl_device_operational(hdev, NULL)) {
                rc = -EPERM;
                goto unlock_and_free_fence;
@@ -2765,7 +2766,7 @@ static int _hl_interrupt_wait_ioctl(struct hl_device *hdev, struct hl_ctx *ctx,
         * handler to monitor
         */
        list_add_tail(&pend->wait_list_node, &interrupt->wait_list_head);
-       spin_unlock(&interrupt->wait_list_lock);
+       spin_unlock_irqrestore(&interrupt->wait_list_lock, flags);
 
 wait_again:
        /* Wait for interrupt handler to signal completion */
@@ -2777,12 +2778,12 @@ wait_again:
         * If comparison fails, keep waiting until timeout expires
         */
        if (completion_rc > 0) {
-               spin_lock(&interrupt->wait_list_lock);
+               spin_lock_irqsave(&interrupt->wait_list_lock, flags);
 
                if (copy_from_user(&completion_value,
                                u64_to_user_ptr(user_address), 4)) {
 
-                       spin_unlock(&interrupt->wait_list_lock);
+                       spin_unlock_irqrestore(&interrupt->wait_list_lock, flags);
 
                        dev_err(hdev->dev,
                                "Failed to copy completion value from user\n");
@@ -2792,13 +2793,13 @@ wait_again:
                }
 
                if (completion_value >= target_value) {
-                       spin_unlock(&interrupt->wait_list_lock);
+                       spin_unlock_irqrestore(&interrupt->wait_list_lock, flags);
                        *status = CS_WAIT_STATUS_COMPLETED;
                } else {
                        reinit_completion(&pend->fence.completion);
                        timeout = completion_rc;
 
-                       spin_unlock(&interrupt->wait_list_lock);
+                       spin_unlock_irqrestore(&interrupt->wait_list_lock, flags);
                        goto wait_again;
                }
        } else if (completion_rc == -ERESTARTSYS) {
@@ -2812,11 +2813,11 @@ wait_again:
        }
 
 remove_pending_user_interrupt:
-       spin_lock(&interrupt->wait_list_lock);
+       spin_lock_irqsave(&interrupt->wait_list_lock, flags);
        list_del(&pend->wait_list_node);
 
 unlock_and_free_fence:
-       spin_unlock(&interrupt->wait_list_lock);
+       spin_unlock_irqrestore(&interrupt->wait_list_lock, flags);
        kfree(pend);
        hl_ctx_put(ctx);