Messages in this thread Patch in this message | | | From | Chengfeng Ye <> | Subject | [PATCH v2 2/2] atm: solos-pci: Fix potential deadlock on &tx_queue_lock | Date | Thu, 5 Oct 2023 07:49:17 +0000 |
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As &card->tx_queue_lock is acquired under softirq context along the following call chain from solos_bh(), other acquisition of the same lock inside process context should disable at least bh to avoid double lock.
<deadlock #2> pclose() --> spin_lock(&card->tx_queue_lock) <interrupt> --> solos_bh() --> fpga_tx() --> spin_lock(&card->tx_queue_lock)
This flaw was found by an experimental static analysis tool I am developing for irq-related deadlock.
To prevent the potential deadlock, the patch uses spin_lock_irqsave() on &card->tx_queue_lock under process context code consistently to prevent the possible deadlock scenario.
Fixes: 213e85d38912 ("solos-pci: clean up pclose() function") Signed-off-by: Chengfeng Ye <dg573847474@gmail.com> --- V2: add fix tag, and split into two patches
drivers/atm/solos-pci.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/atm/solos-pci.c b/drivers/atm/solos-pci.c index 48cf9b36b61a..247e9200e312 100644 --- a/drivers/atm/solos-pci.c +++ b/drivers/atm/solos-pci.c @@ -955,16 +955,17 @@ static void pclose(struct atm_vcc *vcc) unsigned char port = SOLOS_CHAN(vcc->dev); struct sk_buff *skb, *tmpskb; struct pkt_hdr *header; + unsigned long flags; /* Remove any yet-to-be-transmitted packets from the pending queue */ - spin_lock(&card->tx_queue_lock); + spin_lock_irqsave(&card->tx_queue_lock, flags); skb_queue_walk_safe(&card->tx_queue[port], skb, tmpskb) { if (SKB_CB(skb)->vcc == vcc) { skb_unlink(skb, &card->tx_queue[port]); solos_pop(vcc, skb); } } - spin_unlock(&card->tx_queue_lock); + spin_unlock_irqrestore(&card->tx_queue_lock, flags); skb = alloc_skb(sizeof(*header), GFP_KERNEL); if (!skb) { -- 2.17.1
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