[PATCH 5.12 regression fix] brcmfmac: p2p: Fix recently introduced deadlock issue

[PATCH 5.12 regression fix] brcmfmac: p2p: Fix recently introduced deadlock issue

[Hans de Goede]

Commit a05829a7222e ("cfg80211: avoid holding the RTNL when calling the
driver") replaced the rtnl_lock parameter passed to various brcmf
functions with just lock, because since that commit it is not just
about the rtnl_lock but also about the wiphy_lock .

During this search/replace the "if (!rtnl_locked)" check in brcmfmac/p2p.c
was accidentally replaced with "if (locked)", dropping the inversion of
the check. This causes the code to now call rtnl_lock() while already
holding the lock, causing a deadlock.

Add back the "!" to the if-condition to fix this.

Cc: Johannes Berg <johannes.berg@intel.com>
Fixes: a05829a7222e ("cfg80211: avoid holding the RTNL when calling the driver")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c
index 6d30a0fcecea..34cd8a7401fe 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c
@@ -2439,7 +2439,7 @@ void brcmf_p2p_ifp_removed(struct brcmf_if *ifp, bool locked)
 	vif = ifp->vif;
 	cfg = wdev_to_cfg(&vif->wdev);
 	cfg->p2p.bss_idx[P2PAPI_BSSCFG_DEVICE].vif = NULL;
-	if (locked) {
+	if (!locked) {
 		rtnl_lock();
 		wiphy_lock(cfg->wiphy);
 		cfg80211_unregister_wdev(&vif->wdev);
-- 
2.30.2

Re: [PATCH 5.12 regression fix] brcmfmac: p2p: Fix recently introduced deadlock issue

[Johannes Berg]

On Sat, 2021-03-13 at 15:36 +0100, Hans de Goede wrote:
> Commit a05829a7222e ("cfg80211: avoid holding the RTNL when calling the
> driver") replaced the rtnl_lock parameter passed to various brcmf
> functions with just lock, because since that commit it is not just
> about the rtnl_lock but also about the wiphy_lock .
> 
> During this search/replace the "if (!rtnl_locked)" check in brcmfmac/p2p.c
> was accidentally replaced with "if (locked)", dropping the inversion of
> the check. This causes the code to now call rtnl_lock() while already
> holding the lock, causing a deadlock.
> 
> Add back the "!" to the if-condition to fix this.

Ouch, sorry about that, and thanks for the fix!

johannes

Re: [PATCH 5.12 regression fix] brcmfmac: p2p: Fix recently introduced deadlock issue

[Kalle Valo]

Hans de Goede <hdegoede@redhat.com> wrote:

> Commit a05829a7222e ("cfg80211: avoid holding the RTNL when calling the
> driver") replaced the rtnl_lock parameter passed to various brcmf
> functions with just lock, because since that commit it is not just
> about the rtnl_lock but also about the wiphy_lock .
> 
> During this search/replace the "if (!rtnl_locked)" check in brcmfmac/p2p.c
> was accidentally replaced with "if (locked)", dropping the inversion of
> the check. This causes the code to now call rtnl_lock() while already
> holding the lock, causing a deadlock.
> 
> Add back the "!" to the if-condition to fix this.
> 
> Cc: Johannes Berg <johannes.berg@intel.com>
> Fixes: a05829a7222e ("cfg80211: avoid holding the RTNL when calling the driver")
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>

Patch applied to wireless-drivers.git, thanks.

bd83a2fc05ed brcmfmac: p2p: Fix recently introduced deadlock issue

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20210313143635.109154-1-hdegoede@redhat.com/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches