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a7decc44a0
brcmf_msgbuf_ioctl_resp_wake() seems to be missing a memory barrier which might cause the waker to not notice the waiter and miss sending a wake_up as in the following figure. brcmf_msgbuf_ioctl_resp_wake brcmf_msgbuf_ioctl_resp_wait ------------------------------------------------------------------------ if (waitqueue_active(&msgbuf->ioctl_resp_wait)) /* The CPU might reorder the test for the waitqueue up here, before prior writes complete */ /* wait_event_timeout */ /* __wait_event_timeout */ /* ___wait_event */ prepare_to_wait_event(&wq, &__wait, state); if (msgbuf->ctl_completed) ... msgbuf->ctl_completed = true; schedule_timeout(__ret)) ------------------------------------------------------------------------ There are three other place in drivers/net/wireless/brcm80211/brcmfmac/ which have similar code. The attached patch removes the call to waitqueue_active() leaving just wake_up() behind. This fixes the problem because the call to spin_lock_irqsave() in wake_up() will be an ACQUIRE operation. I found this issue when I was looking through the linux source code for places calling waitqueue_active() before wake_up*(), but without preceding memory barriers, after sending a patch to fix a similar issue in drivers/tty/n_tty.c (Details about the original issue can be found here: https://lkml.org/lkml/2015/9/28/849). Reviewed-by: Hante Meuleman <meuleman@broadcom.com> Reviewed-by: Franky (Zhenhui) Lin <frankyl@broadcom.com> Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com> Signed-off-by: Kosuke Tatsukawa <tatsu@ab.jp.nec.com> Signed-off-by: Arend van Spriel <arend@broadcom.com> Signed-off-by: Kalle Valo <kvalo@codeaurora.org> |
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| admtek | ||
| ath | ||
| atmel | ||
| broadcom | ||
| cisco | ||
| intel | ||
| intersil | ||
| marvell | ||
| mediatek | ||
| ralink | ||
| realtek | ||
| rsi | ||
| st | ||
| ti | ||
| zydas | ||
| Kconfig | ||
| mac80211_hwsim.c | ||
| mac80211_hwsim.h | ||
| Makefile | ||
| ray_cs.c | ||
| ray_cs.h | ||
| rayctl.h | ||
| rndis_wlan.c | ||
| wl3501_cs.c | ||
| wl3501.h | ||