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Commit 07681e21 authored by Michael Buesch's avatar Michael Buesch Committed by John W. Linville
Browse files

b43: Rewrite DMA Tx status handling sanity checks 



This rewrites the error handling policies in the TX status handler.
It tries to be error-tolerant as in "try hard to not crash the machine".
It won't recover from errors (that are bugs in the firmware or driver),
because that's impossible. However, it will return a more or less useful
error message and bail out. It also tries hard to use rate-limited messages
to not flood the syslog in case of a failure.

Signed-off-by: default avatarMichael Buesch <mb@bu3sch.de>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 8c35024a

drivers/net/wireless/b43/dma.c

+54 −13
Original line number Diff line number Diff line
@@ -874,7 +874,7 @@ static void free_all_descbuffers(struct b43_dmaring *ring) 
	for (i = 0; i < ring->nr_slots; i++) {

		desc = ring->ops->idx2desc(ring, i, &meta);



		if (!meta->skb) {

		if (!meta->skb || b43_dma_ptr_is_poisoned(meta->skb)) {

			B43_WARN_ON(!ring->tx);

			continue;

		}
@@ -926,7 +926,7 @@ struct b43_dmaring *b43_setup_dmaring(struct b43_wldev *dev, 
				      enum b43_dmatype type)

{

	struct b43_dmaring *ring;

	int err;

	int i, err;

	dma_addr_t dma_test;



	ring = kzalloc(sizeof(*ring), GFP_KERNEL);
@@ -941,6 +941,8 @@ struct b43_dmaring *b43_setup_dmaring(struct b43_wldev *dev, 
			     GFP_KERNEL);

	if (!ring->meta)

		goto err_kfree_ring;

	for (i = 0; i < ring->nr_slots; i++)

		ring->meta->skb = B43_DMA_PTR_POISON;



	ring->type = type;

	ring->dev = dev;
@@ -1251,11 +1253,13 @@ struct b43_dmaring *parse_cookie(struct b43_wldev *dev, u16 cookie, int *slot) 
	case 0x5000:

		ring = dma->tx_ring_mcast;

		break;

	default:

		B43_WARN_ON(1);

	}

	*slot = (cookie & 0x0FFF);

	B43_WARN_ON(!(ring && *slot >= 0 && *slot < ring->nr_slots));

	if (unlikely(!ring || *slot < 0 || *slot >= ring->nr_slots)) {

		b43dbg(dev->wl, "TX-status contains "

		       "invalid cookie: 0x%04X\n", cookie);

		return NULL;

	}



	return ring;

}
@@ -1494,19 +1498,40 @@ void b43_dma_handle_txstatus(struct b43_wldev *dev, 
	struct b43_dmaring *ring;

	struct b43_dmadesc_generic *desc;

	struct b43_dmadesc_meta *meta;

	int slot;

	int slot, firstused;

	bool frame_succeed;



	ring = parse_cookie(dev, status->cookie, &slot);

	if (unlikely(!ring))

		return;



	B43_WARN_ON(!ring->tx);



	/* Sanity check: TX packets are processed in-order on one ring.

	 * Check if the slot deduced from the cookie really is the first

	 * used slot. */

	firstused = ring->current_slot - ring->used_slots + 1;

	if (firstused < 0)

		firstused = ring->nr_slots + firstused;

	if (unlikely(slot != firstused)) {

		/* This possibly is a firmware bug and will result in

		 * malfunction, memory leaks and/or stall of DMA functionality. */

		b43dbg(dev->wl, "Out of order TX status report on DMA ring %d. "

		       "Expected %d, but got %d\n",

		       ring->index, firstused, slot);

		return;

	}



	ops = ring->ops;

	while (1) {

		B43_WARN_ON(!(slot >= 0 && slot < ring->nr_slots));

		B43_WARN_ON(slot < 0 || slot >= ring->nr_slots);

		desc = ops->idx2desc(ring, slot, &meta);



		if (b43_dma_ptr_is_poisoned(meta->skb)) {

			b43dbg(dev->wl, "Poisoned TX slot %d (first=%d) "

			       "on ring %d\n",

			       slot, firstused, ring->index);

			break;

		}

		if (meta->skb) {

			struct b43_private_tx_info *priv_info =

				b43_get_priv_tx_info(IEEE80211_SKB_CB(meta->skb));
@@ -1522,7 +1547,14 @@ void b43_dma_handle_txstatus(struct b43_wldev *dev, 
		if (meta->is_last_fragment) {

			struct ieee80211_tx_info *info;



			BUG_ON(!meta->skb);

			if (unlikely(!meta->skb)) {

				/* This is a scatter-gather fragment of a frame, so

				 * the skb pointer must not be NULL. */

				b43dbg(dev->wl, "TX status unexpected NULL skb "

				       "at slot %d (first=%d) on ring %d\n",

				       slot, firstused, ring->index);

				break;

			}



			info = IEEE80211_SKB_CB(meta->skb);
@@ -1540,20 +1572,29 @@ void b43_dma_handle_txstatus(struct b43_wldev *dev, 
#endif /* DEBUG */

			ieee80211_tx_status(dev->wl->hw, meta->skb);



			/* skb is freed by ieee80211_tx_status() */

			meta->skb = NULL;

			/* skb will be freed by ieee80211_tx_status().

			 * Poison our pointer. */

			meta->skb = B43_DMA_PTR_POISON;

		} else {

			/* No need to call free_descriptor_buffer here, as

			 * this is only the txhdr, which is not allocated.

			 */

			B43_WARN_ON(meta->skb);

			if (unlikely(meta->skb)) {

				b43dbg(dev->wl, "TX status unexpected non-NULL skb "

				       "at slot %d (first=%d) on ring %d\n",

				       slot, firstused, ring->index);

				break;

			}

		}



		/* Everything unmapped and free'd. So it's not used anymore. */

		ring->used_slots--;



		if (meta->is_last_fragment)

		if (meta->is_last_fragment) {

			/* This is the last scatter-gather

			 * fragment of the frame. We are done. */

			break;

		}

		slot = next_slot(ring, slot);

	}

	if (ring->stopped) {

drivers/net/wireless/b43/dma.h

+5 −1
Original line number Diff line number Diff line 
#ifndef B43_DMA_H_

#define B43_DMA_H_



#include <linux/ieee80211.h>

#include <linux/err.h>



#include "b43.h"
@@ -164,6 +164,10 @@ struct b43_dmadesc_generic { 
#define B43_RXRING_SLOTS		64

#define B43_DMA0_RX_BUFFERSIZE		IEEE80211_MAX_FRAME_LEN



/* Pointer poison */

#define B43_DMA_PTR_POISON		((void *)ERR_PTR(-ENOMEM))

#define b43_dma_ptr_is_poisoned(ptr)	(unlikely((ptr) == B43_DMA_PTR_POISON))





struct sk_buff;

struct b43_private;