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[ Upstream commit b55379e343a3472c35f4a1245906db5158cab453 ] Failed to transmit wmi management frames: [84977.840894] ath10k_snoc a000000.wifi: wmi mgmt tx queue is full [84977.840913] ath10k_snoc a000000.wifi: failed to transmit packet, dropping: -28 [84977.840924] ath10k_snoc a000000.wifi: failed to submit frame: -28 [84977.840932] ath10k_snoc a000000.wifi: failed to transmit frame: -28 This issue is caused by race condition between skb_dequeue and __skb_queue_tail. The queue of ‘wmi_mgmt_tx_queue’ is protected by a different lock: ar->data_lock vs list->lock, the result is no protection. So when ath10k_mgmt_over_wmi_tx_work() and ath10k_mac_tx_wmi_mgmt() running concurrently on different CPUs, there appear to be a rare corner cases when the queue length is 1, CPUx (skb_deuque) CPUy (__skb_queue_tail) next=list prev=list struct sk_buff *skb = skb_peek(list); WRITE_ONCE(newsk->next, next); WRITE_ONCE(list->qlen, list->qlen - 1);WRITE_ONCE(newsk->prev, prev); next = skb->next; WRITE_ONCE(next->prev, newsk); prev = skb->prev; WRITE_ONCE(prev->next, newsk); skb->next = skb->prev = NULL; list->qlen++; WRITE_ONCE(next->prev, prev); WRITE_ONCE(prev->next, next); If the instruction ‘next = skb->next’ is executed before ‘WRITE_ONCE(prev->next, newsk)’, newsk will be lost, as CPUx get the old ‘next’ pointer, but the length is still added by one. The final result is the length of the queue will reach the maximum value but the queue is empty. So remove ar->data_lock, and use 'skb_queue_tail' instead of '__skb_queue_tail' to prevent the potential race condition. Also switch to use skb_queue_len_lockless, in case we queue a few SKBs simultaneously. Tested-on: WCN3990 hw1.0 SNOC WLAN.HL.3.1.c2-00033-QCAHLSWMTPLZ-1 Signed-off-by: Miaoqing Pan <miaoqing@codeaurora.org> Reviewed-by: Brian Norris <briannorris@chromium.org> Signed-off-by: Kalle Valo <kvalo@codeaurora.org> Link: https://lore.kernel.org/r/1608618887-8857-1-git-send-email-miaoqing@codeaurora.org Signed-off-by: Sasha Levin <sashal@kernel.org> |
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| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
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| .clang-format | ||
| .cocciconfig | ||
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| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.