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[80.56.215.227]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-311838c9235sm39074609eec.21.2026.07.10.12.18.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 10 Jul 2026 12:18:27 -0700 (PDT) Message-ID: Date: Fri, 10 Jul 2026 21:18:21 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] wifi: brcmfmac: drain bus_reset work on device removal To: Eddie Phillips , Fan Wu Cc: Arend van Spriel , Kalle Valo , Franky Lin , Hante Meuleman , Chi-Hsien Lin , Wright Feng , Chung-Hsien Hsu , "David S . Miller" , Jakub Kicinski , linux-wireless@vger.kernel.org, brcm80211-dev-list.pdl@broadcom.com, SHA-cyfmac-dev-list@infineon.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20260709101635.103005-1-fanwu01@zju.edu.cn> <20260710002451.500112-1-eddiephillips@google.com> Content-Language: en-US From: Arend van Spriel In-Reply-To: <20260710002451.500112-1-eddiephillips@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-DetectorID-Processed: b00c1d49-9d2e-4205-b15f-d015386d3d5e On 10/07/2026 02:23, Eddie Phillips wrote: > On Thu, 9 Jul 2026 10:16:35 +0000 Fan Wu wrote: > >> brcmf_fw_crashed() and the debugfs "reset" entry both schedule >> drvr->bus_reset, whose callback recovers drvr through container_of() >> and dereferences it. The teardown paths free drvr (brcmf_free -> >> wiphy_free) without draining the work, so a bus_reset callback pending >> or running during removal can outlive drvr. >> [...] >> >> This issue was found by an in-house static analysis tool. >> >> Fixes: 4684997d9eea ("brcmfmac: reset PCIe bus on a firmware crash") >> Cc: stable@vger.kernel.org >> Signed-off-by: Fan Wu >> Assisted-by: Codex:gpt-5.5 >> --- >> .../broadcom/brcm80211/brcmfmac/bcmsdh.c | 13 ++++++++ >> .../broadcom/brcm80211/brcmfmac/bus.h | 6 ++++ >> .../broadcom/brcm80211/brcmfmac/core.c | 33 +++++++++++++++++-- >> .../broadcom/brcm80211/brcmfmac/pcie.c | 6 ++++ >> .../broadcom/brcm80211/brcmfmac/sdio.c | 6 ++++ >> .../broadcom/brcm80211/brcmfmac/sdio.h | 1 + >> .../broadcom/brcm80211/brcmfmac/usb.c | 3 ++ >> 7 files changed, 66 insertions(+), 2 deletions(-) [...] >> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c >> index fed9cd5f2..b934feb9b 100644 >> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c >> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c >> @@ -1164,6 +1164,35 @@ static int brcmf_revinfo_read(struct seq_file *s, void *data) >> return 0; >> } >> >> +/* Serialize bus_reset arming (debugfs reset write, brcmf_fw_crashed) against the >> + * teardown drain: the remove path takes bus_reset_lock, sets ->removing and cancels >> + * the work under it, so a racing armer either schedules before the cancel (and is >> + * drained) or observes ->removing and desists. >> + */ >> +static void brcmf_bus_schedule_reset(struct brcmf_bus *bus_if) >> +{ >> + mutex_lock(&bus_if->bus_reset_lock); >> + if (bus_if->drvr && bus_if->drvr->bus_reset.func && !bus_if->removing) >> + schedule_work(&bus_if->drvr->bus_reset); >> + mutex_unlock(&bus_if->bus_reset_lock); >> +} > > Is this safe in a softIRQ context? > mutex_lock() sleeps until it can get the lock. What softIRQ context? brcmf_fw_crashed() is called by PCIe (thread) and SDIO (worker). >> + >> +void brcmf_bus_cancel_reset_work(struct brcmf_bus *bus_if) >> +{ >> + mutex_lock(&bus_if->bus_reset_lock); >> + bus_if->removing = true; >> + if (bus_if->drvr) >> + cancel_work_sync(&bus_if->drvr->bus_reset); >> + mutex_unlock(&bus_if->bus_reset_lock); >> +} > > How about if brcmf_pcie_remove() calls brcmf_bus_cancel_reset_work(), > takes the lock and calls cancel_work_sync(), sleeps. If debugfs > path is already running, it can invoke the worker thread. Is there > potential that both try to reset? What is "both" here? Regards, Arend