Messages in this thread Patch in this message | | | Date | Fri, 21 Apr 2006 18:45:51 -0500 | Subject | [PATCH 2/2]: Spider ethernet driver -- protect chain head | From | (Linas Vepstas) |
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Please review/apply/ack/forward upstream.
--linas
Prevent a potential race. If two threads are both calling the transmit routine, both can potentially try to grab the same dma descriptor. Serialize access to the head of the tx ring with spinlocks.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
---- drivers/net/spider_net.c | 12 ++++++++---- 1 files changed, 8 insertions(+), 4 deletions(-)
Index: linux-2.6.17-rc1/drivers/net/spider_net.c =================================================================== --- linux-2.6.17-rc1.orig/drivers/net/spider_net.c 2006-04-21 18:32:46.000000000 -0500 +++ linux-2.6.17-rc1/drivers/net/spider_net.c 2006-04-21 18:39:12.000000000 -0500 @@ -806,13 +806,19 @@ spider_net_stop(struct net_device *netde static struct spider_net_descr * spider_net_get_next_tx_descr(struct spider_net_card *card) { + struct spider_net_descr *descr; + spin_lock(&card->tx_chain_lock); + + descr = card->tx_chain.head; /* check, if head points to not-in-use descr */ if ( spider_net_get_descr_status(card->tx_chain.head) == SPIDER_NET_DESCR_NOT_IN_USE ) { - return card->tx_chain.head; + card->tx_chain.head = descr->next; } else { - return NULL; + descr = NULL; } + spin_unlock(&card->tx_chain_lock); + return descr; } /** @@ -932,8 +938,6 @@ spider_net_xmit(struct sk_buff *skb, str if (result) goto error; - card->tx_chain.head = card->tx_chain.head->next; - if (spider_net_get_descr_status(descr->prev) != SPIDER_NET_DESCR_CARDOWNED) { /* make sure the current descriptor is in memory. Then - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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