[][Backport napi releated bug fixes to openwrt 21.02]
[Description]
Add some napi releated bug fixeds to openwrt 21.02
Please refer to following patches for detail:
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/net/core/dev.c?id=0315a075f1343966ea2d9a085666a88a69ea6a3d
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/net/core/dev.c?id=3765996e4f0b8a755cab215a08df744490c76052
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/net/core/dev.c?id=719c571970109b0d0af24745d31b202affc9365f
Please notice following changed:
+ new &= ~(NAPIF_STATE_THREADED | NAPIF_STATE_PREFER_BUSY_POLL);
/* No "NAPIF_STATE_PREFER_BUSY_POLL" in kernel 5.4 */
- clear_bit(NAPI_STATE_PREFER_BUSY_POLL, &n->state);
Test: Build PASS
[Release-log]
N/A
Change-Id: Icb0d352821fb91108eb08f46f8bda8f1419f7777
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/6050622
diff --git a/target/linux/mediatek/patches-5.4/7002-net-fix-premature-exit-from-napi-state-polling-in-napi-disable-v2.patch b/target/linux/mediatek/patches-5.4/7002-net-fix-premature-exit-from-napi-state-polling-in-napi-disable-v2.patch
new file mode 100644
index 0000000..0daf233
--- /dev/null
+++ b/target/linux/mediatek/patches-5.4/7002-net-fix-premature-exit-from-napi-state-polling-in-napi-disable-v2.patch
@@ -0,0 +1,114 @@
+From git@z Thu Jan 1 00:00:00 1970
+Subject: [PATCH v2] net: fix premature exit from NAPI state polling in napi_disable()
+From: Alexander Lobakin <alexandr.lobakin@intel.com>
+Date: Wed, 10 Nov 2021 20:56:05 +0100
+Message-Id: <20211110195605.1304-1-alexandr.lobakin@intel.com>
+To: "David S. Miller" <davem@davemloft.net>, Jakub Kicinski <kuba@kernel.org>
+Cc: Alexander Lobakin <alexandr.lobakin@intel.com>, Jesse Brandeburg <jesse.brandeburg@intel.com>, Maciej Fijalkowski <maciej.fijalkowski@intel.com>, Michal Swiatkowski <michal.swiatkowski@intel.com>, Xuan Zhuo <xuanzhuo@linux.alibaba.com>, Antoine Tenart <atenart@kernel.org>, Eric Dumazet <edumazet@google.com>, Wei Wang <weiwan@google.com>,Björn Töpel <bjorn@kernel.org>, netdev@vger.kernel.org, linux-kernel@vger.kernel.org
+List-Id: <linux-kernel.vger.kernel.org>
+MIME-Version: 1.0
+Content-Type: text/plain; charset="utf-8"
+Content-Transfer-Encoding: 7bit
+
+Commit 719c57197010 ("net: make napi_disable() symmetric with
+enable") accidentally introduced a bug sometimes leading to a kernel
+BUG when bringing an iface up/down under heavy traffic load.
+
+Prior to this commit, napi_disable() was polling n->state until
+none of (NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC) is set and then
+always flip them. Now there's a possibility to get away with the
+NAPIF_STATE_SCHE unset as 'continue' drops us to the cmpxchg()
+call with an unitialized variable, rather than straight to
+another round of the state check.
+
+Error path looks like:
+
+napi_disable():
+unsigned long val, new; /* new is uninitialized */
+
+do {
+ val = READ_ONCE(n->state); /* NAPIF_STATE_NPSVC and/or
+ NAPIF_STATE_SCHED is set */
+ if (val & (NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC)) { /* true */
+ usleep_range(20, 200);
+ continue; /* go straight to the condition check */
+ }
+ new = val | <...>
+} while (cmpxchg(&n->state, val, new) != val); /* state == val, cmpxchg()
+ writes garbage */
+
+napi_enable():
+do {
+ val = READ_ONCE(n->state);
+ BUG_ON(!test_bit(NAPI_STATE_SCHED, &val)); /* 50/50 boom */
+<...>
+
+while the typical BUG splat is like:
+
+[ 172.652461] ------------[ cut here ]------------
+[ 172.652462] kernel BUG at net/core/dev.c:6937!
+[ 172.656914] invalid opcode: 0000 [#1] PREEMPT SMP PTI
+[ 172.661966] CPU: 36 PID: 2829 Comm: xdp_redirect_cp Tainted: G I 5.15.0 #42
+[ 172.670222] Hardware name: Intel Corporation S2600WFT/S2600WFT, BIOS SE5C620.86B.02.01.0014.082620210524 08/26/2021
+[ 172.680646] RIP: 0010:napi_enable+0x5a/0xd0
+[ 172.684832] Code: 07 49 81 cc 00 01 00 00 4c 89 e2 48 89 d8 80 e6 fb f0 48 0f b1 55 10 48 39 c3 74 10 48 8b 5d 10 f6 c7 04 75 3d f6 c3 01 75 b4 <0f> 0b 5b 5d 41 5c c3 65 ff 05 b8 e5 61 53 48 c7 c6 c0 f3 34 ad 48
+[ 172.703578] RSP: 0018:ffffa3c9497477a8 EFLAGS: 00010246
+[ 172.708803] RAX: ffffa3c96615a014 RBX: 0000000000000000 RCX: ffff8a4b575301a0
+< snip >
+[ 172.782403] Call Trace:
+[ 172.784857] <TASK>
+[ 172.786963] ice_up_complete+0x6f/0x210 [ice]
+[ 172.791349] ice_xdp+0x136/0x320 [ice]
+[ 172.795108] ? ice_change_mtu+0x180/0x180 [ice]
+[ 172.799648] dev_xdp_install+0x61/0xe0
+[ 172.803401] dev_xdp_attach+0x1e0/0x550
+[ 172.807240] dev_change_xdp_fd+0x1e6/0x220
+[ 172.811338] do_setlink+0xee8/0x1010
+[ 172.814917] rtnl_setlink+0xe5/0x170
+[ 172.818499] ? bpf_lsm_binder_set_context_mgr+0x10/0x10
+[ 172.823732] ? security_capable+0x36/0x50
+< snip >
+
+Fix this by replacing 'do { } while (cmpxchg())' with an "infinite"
+for-loop with an explicit break.
+
+From v1 [0]:
+ - just use a for-loop to simplify both the fix and the existing
+ code (Eric).
+
+[0] https://lore.kernel.org/netdev/20211110191126.1214-1-alexandr.lobakin@intel.com
+
+Fixes: 719c57197010 ("net: make napi_disable() symmetric with enable")
+Suggested-by: Eric Dumazet <edumazet@google.com> # for-loop
+Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
+Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
+Reviewed-by: Eric Dumazet <edumazet@google.com>
+---
+ net/core/dev.c | 7 +++++--
+ 1 file changed, 5 insertions(+), 2 deletions(-)
+
+diff --git a/net/core/dev.c b/net/core/dev.c
+index c8f7c15..fe2c856 100644
+--- a/net/core/dev.c
++++ b/net/core/dev.c
+@@ -6391,7 +6391,7 @@ void napi_disable(struct napi_struct *n)
+ might_sleep();
+ set_bit(NAPI_STATE_DISABLE, &n->state);
+
+- do {
++ for ( ; ; ) {
+ val = READ_ONCE(n->state);
+ if (val & (NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC)) {
+ usleep_range(20, 200);
+@@ -6400,7 +6400,10 @@ void napi_disable(struct napi_struct *n)
+
+ new = val | NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC;
+ new &= ~(NAPIF_STATE_THREADED);
+- } while (cmpxchg(&n->state, val, new) != val);
++
++ if (cmpxchg(&n->state, val, new) == val)
++ break;
++ }
+
+ hrtimer_cancel(&n->timer);
+