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Commit d1f41597 authored by Raja Mani's avatar Raja Mani Committed by Kalle Valo
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ath6kl: Fix random system lockup 



The commit "ath6kl: Use a mutex_lock to avoid
race in diabling and handling irq" introduces a
state where ath6kl_sdio_irq_handler() would be waiting
to claim the sdio function for receive indefinitely
when things happen in the following order.

ath6kl_sdio_irq_handler()
	- aquires mtx_irq
	- sdio_release_host()
					ath6kl_sdio_irq_disable()
						- sdio_claim_host()
						- sleep on mtx_irq
	ath6kl_hif_intr_bh_handler()
		- (indefinitely) wait for the sdio
		  function to be released to exclusively claim
		  it again for receive operation.

Fix this by replacing the mtx_irq with an atomic
variable and a wait_queue.

kvalo: add ath6kl_sdio_is_on_irq() due to open parenthesis alignment

Signed-off-by: default avatarRaja Mani <rmani@qca.qualcomm.com>
Signed-off-by: default avatarVasanthakumar Thiagarajan <vthiagar@qca.qualcomm.com>
Signed-off-by: default avatarKalle Valo <kvalo@qca.qualcomm.com>
parent af840ba7

drivers/net/wireless/ath/ath6kl/sdio.c

+26 −8
Original line number Diff line number Diff line
@@ -50,8 +50,8 @@ struct ath6kl_sdio { 
	/* scatter request list head */

	struct list_head scat_req;



	/* Avoids disabling irq while the interrupts being handled */

	struct mutex mtx_irq;

	atomic_t irq_handling;

	wait_queue_head_t irq_wq;



	spinlock_t scat_lock;

	bool scatter_enabled;
@@ -463,7 +463,7 @@ static void ath6kl_sdio_irq_handler(struct sdio_func *func) 
	ath6kl_dbg(ATH6KL_DBG_SDIO, "irq\n");



	ar_sdio = sdio_get_drvdata(func);

	mutex_lock(&ar_sdio->mtx_irq);

	atomic_set(&ar_sdio->irq_handling, 1);

	/*

	 * Release the host during interrups so we can pick it back up when

	 * we process commands.
@@ -472,7 +472,10 @@ static void ath6kl_sdio_irq_handler(struct sdio_func *func) 


	status = ath6kl_hif_intr_bh_handler(ar_sdio->ar);

	sdio_claim_host(ar_sdio->func);

	mutex_unlock(&ar_sdio->mtx_irq);



	atomic_set(&ar_sdio->irq_handling, 0);

	wake_up(&ar_sdio->irq_wq);



	WARN_ON(status && status != -ECANCELED);

}
@@ -573,6 +576,13 @@ static void ath6kl_sdio_irq_enable(struct ath6kl *ar) 
	sdio_release_host(ar_sdio->func);

}



static bool ath6kl_sdio_is_on_irq(struct ath6kl *ar)

{

	struct ath6kl_sdio *ar_sdio = ath6kl_sdio_priv(ar);



	return !atomic_read(&ar_sdio->irq_handling);

}



static void ath6kl_sdio_irq_disable(struct ath6kl *ar)

{

	struct ath6kl_sdio *ar_sdio = ath6kl_sdio_priv(ar);
@@ -580,14 +590,21 @@ static void ath6kl_sdio_irq_disable(struct ath6kl *ar) 


	sdio_claim_host(ar_sdio->func);



	mutex_lock(&ar_sdio->mtx_irq);

	if (atomic_read(&ar_sdio->irq_handling)) {

		sdio_release_host(ar_sdio->func);



		ret = wait_event_interruptible(ar_sdio->irq_wq,

					       ath6kl_sdio_is_on_irq(ar));

		if (ret)

			return;



		sdio_claim_host(ar_sdio->func);

	}



	ret = sdio_release_irq(ar_sdio->func);

	if (ret)

		ath6kl_err("Failed to release sdio irq: %d\n", ret);



	mutex_unlock(&ar_sdio->mtx_irq);



	sdio_release_host(ar_sdio->func);

}
@@ -1288,7 +1305,6 @@ static int ath6kl_sdio_probe(struct sdio_func *func, 
	spin_lock_init(&ar_sdio->scat_lock);

	spin_lock_init(&ar_sdio->wr_async_lock);

	mutex_init(&ar_sdio->dma_buffer_mutex);

	mutex_init(&ar_sdio->mtx_irq);



	INIT_LIST_HEAD(&ar_sdio->scat_req);

	INIT_LIST_HEAD(&ar_sdio->bus_req_freeq);
@@ -1296,6 +1312,8 @@ static int ath6kl_sdio_probe(struct sdio_func *func, 


	INIT_WORK(&ar_sdio->wr_async_work, ath6kl_sdio_write_async_work);



	init_waitqueue_head(&ar_sdio->irq_wq);



	for (count = 0; count < BUS_REQUEST_MAX_NUM; count++)

		ath6kl_sdio_free_bus_req(ar_sdio, &ar_sdio->bus_req[count]);