From: Joshua Washington Date: Tue, 22 Apr 2025 01:16:32 +0000 (-0700) Subject: xdp: create locked/unlocked instances of xdp redirect target setters X-Git-Tag: v6.16-rc1~132^2~239 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=0e0a7e3719bc8cbe6d6e30b3e81f21472ecba5bc;p=thirdparty%2Flinux.git xdp: create locked/unlocked instances of xdp redirect target setters Commit 03df156dd3a6 ("xdp: double protect netdev->xdp_flags with netdev->lock") introduces the netdev lock to xdp_set_features_flag(). The change includes a _locked version of the method, as it is possible for a driver to have already acquired the netdev lock before calling this helper. However, the same applies to xdp_features_(set|clear)_redirect_flags(), which ends up calling the unlocked version of xdp_set_features_flags() leading to deadlocks in GVE, which grabs the netdev lock as part of its suspend, reset, and shutdown processes: [ 833.265543] WARNING: possible recursive locking detected [ 833.270949] 6.15.0-rc1 #6 Tainted: G E [ 833.276271] -------------------------------------------- [ 833.281681] systemd-shutdow/1 is trying to acquire lock: [ 833.287090] ffff949d2b148c68 (&dev->lock){+.+.}-{4:4}, at: xdp_set_features_flag+0x29/0x90 [ 833.295470] [ 833.295470] but task is already holding lock: [ 833.301400] ffff949d2b148c68 (&dev->lock){+.+.}-{4:4}, at: gve_shutdown+0x44/0x90 [gve] [ 833.309508] [ 833.309508] other info that might help us debug this: [ 833.316130] Possible unsafe locking scenario: [ 833.316130] [ 833.322142] CPU0 [ 833.324681] ---- [ 833.327220] lock(&dev->lock); [ 833.330455] lock(&dev->lock); [ 833.333689] [ 833.333689] *** DEADLOCK *** [ 833.333689] [ 833.339701] May be due to missing lock nesting notation [ 833.339701] [ 833.346582] 5 locks held by systemd-shutdow/1: [ 833.351205] #0: ffffffffa9c89130 (system_transition_mutex){+.+.}-{4:4}, at: __se_sys_reboot+0xe6/0x210 [ 833.360695] #1: ffff93b399e5c1b8 (&dev->mutex){....}-{4:4}, at: device_shutdown+0xb4/0x1f0 [ 833.369144] #2: ffff949d19a471b8 (&dev->mutex){....}-{4:4}, at: device_shutdown+0xc2/0x1f0 [ 833.377603] #3: ffffffffa9eca050 (rtnl_mutex){+.+.}-{4:4}, at: gve_shutdown+0x33/0x90 [gve] [ 833.386138] #4: ffff949d2b148c68 (&dev->lock){+.+.}-{4:4}, at: gve_shutdown+0x44/0x90 [gve] Introduce xdp_features_(set|clear)_redirect_target_locked() versions which assume that the netdev lock has already been acquired before setting the XDP feature flag and update GVE to use the locked version. Fixes: 03df156dd3a6 ("xdp: double protect netdev->xdp_flags with netdev->lock") Tested-by: Mina Almasry Reviewed-by: Willem de Bruijn Reviewed-by: Harshitha Ramamurthy Signed-off-by: Joshua Washington Acked-by: Stanislav Fomichev Acked-by: Martin KaFai Lau Link: https://patch.msgid.link/20250422011643.3509287-1-joshwash@google.com Signed-off-by: Jakub Kicinski --- diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c index 8aaac91013777..446e4b6fd3f17 100644 --- a/drivers/net/ethernet/google/gve/gve_main.c +++ b/drivers/net/ethernet/google/gve/gve_main.c @@ -1830,7 +1830,7 @@ static void gve_turndown(struct gve_priv *priv) /* Stop tx queues */ netif_tx_disable(priv->dev); - xdp_features_clear_redirect_target(priv->dev); + xdp_features_clear_redirect_target_locked(priv->dev); gve_clear_napi_enabled(priv); gve_clear_report_stats(priv); @@ -1902,7 +1902,7 @@ static void gve_turnup(struct gve_priv *priv) } if (priv->tx_cfg.num_xdp_queues && gve_supports_xdp_xmit(priv)) - xdp_features_set_redirect_target(priv->dev, false); + xdp_features_set_redirect_target_locked(priv->dev, false); gve_set_napi_enabled(priv); } diff --git a/include/net/xdp.h b/include/net/xdp.h index 20e41b5ff319a..b40f1f96cb117 100644 --- a/include/net/xdp.h +++ b/include/net/xdp.h @@ -618,7 +618,10 @@ bool bpf_dev_bound_kfunc_id(u32 btf_id); void xdp_set_features_flag(struct net_device *dev, xdp_features_t val); void xdp_set_features_flag_locked(struct net_device *dev, xdp_features_t val); void xdp_features_set_redirect_target(struct net_device *dev, bool support_sg); +void xdp_features_set_redirect_target_locked(struct net_device *dev, + bool support_sg); void xdp_features_clear_redirect_target(struct net_device *dev); +void xdp_features_clear_redirect_target_locked(struct net_device *dev); #else static inline u32 bpf_xdp_metadata_kfunc_id(int id) { return 0; } static inline bool bpf_dev_bound_kfunc_id(u32 btf_id) { return false; } diff --git a/net/core/xdp.c b/net/core/xdp.c index a014df88620cb..ea819764ae39a 100644 --- a/net/core/xdp.c +++ b/net/core/xdp.c @@ -1014,21 +1014,38 @@ void xdp_set_features_flag(struct net_device *dev, xdp_features_t val) } EXPORT_SYMBOL_GPL(xdp_set_features_flag); -void xdp_features_set_redirect_target(struct net_device *dev, bool support_sg) +void xdp_features_set_redirect_target_locked(struct net_device *dev, + bool support_sg) { xdp_features_t val = (dev->xdp_features | NETDEV_XDP_ACT_NDO_XMIT); if (support_sg) val |= NETDEV_XDP_ACT_NDO_XMIT_SG; - xdp_set_features_flag(dev, val); + xdp_set_features_flag_locked(dev, val); +} +EXPORT_SYMBOL_GPL(xdp_features_set_redirect_target_locked); + +void xdp_features_set_redirect_target(struct net_device *dev, bool support_sg) +{ + netdev_lock(dev); + xdp_features_set_redirect_target_locked(dev, support_sg); + netdev_unlock(dev); } EXPORT_SYMBOL_GPL(xdp_features_set_redirect_target); -void xdp_features_clear_redirect_target(struct net_device *dev) +void xdp_features_clear_redirect_target_locked(struct net_device *dev) { xdp_features_t val = dev->xdp_features; val &= ~(NETDEV_XDP_ACT_NDO_XMIT | NETDEV_XDP_ACT_NDO_XMIT_SG); - xdp_set_features_flag(dev, val); + xdp_set_features_flag_locked(dev, val); +} +EXPORT_SYMBOL_GPL(xdp_features_clear_redirect_target_locked); + +void xdp_features_clear_redirect_target(struct net_device *dev) +{ + netdev_lock(dev); + xdp_features_clear_redirect_target_locked(dev); + netdev_unlock(dev); } EXPORT_SYMBOL_GPL(xdp_features_clear_redirect_target);