linux-kernel - [PATCH v1 1/5] idpf: address an rtnl lock splat in tx timeout recovery path

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Message-ID: <20240813182747.1770032-2-manojvishy@google.com>
Date: Tue, 13 Aug 2024 18:27:43 +0000
From: Manoj Vishwanathan <manojvishy@...gle.com>
To: Tony Nguyen <anthony.l.nguyen@...el.com>, 
	Przemek Kitszel <przemyslaw.kitszel@...el.com>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, intel-wired-lan@...ts.osuosl.org
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
	google-lan-reviews@...glegroups.com, 
	Manoj Vishwanathan <manojvishy@...gle.com>
Subject: [PATCH v1 1/5] idpf: address an rtnl lock splat in tx timeout
 recovery path

Adopt the same pattern as in other places in the code to take the rtnl
lock during hard resets.
Tested the patch by injecting tx timeout in IDPF , observe that idpf
recovers and IDPF comes back reachable

Without this patch causes there is a splat:
[  270.145214] WARNING: CPU:  PID:  at net/sched/sch_generic.c:534 dev_watchdog

Signed-off-by: Manoj Vishwanathan <manojvishy@...gle.com>
---
 drivers/net/ethernet/intel/idpf/idpf_txrx.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.c b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
index af2879f03b8d..3c01be90fa75 100644
--- a/drivers/net/ethernet/intel/idpf/idpf_txrx.c
+++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
@@ -4328,14 +4328,26 @@ int idpf_vport_intr_init(struct idpf_vport *vport)
 {
 	char *int_name;
 	int err;
+	bool hr_reset_in_prog;
 
 	err = idpf_vport_intr_init_vec_idx(vport);
 	if (err)
 		return err;
 
 	idpf_vport_intr_map_vector_to_qs(vport);
+	/**
+	 * If we're in normal up path, the stack already takes the
+	 * rtnl_lock for us, however, if we're doing up as a part of a
+	 * hard reset, we'll need to take the lock ourself before
+	 * touching the netdev.
+	 */
+	hr_reset_in_prog = test_bit(IDPF_HR_RESET_IN_PROG,
+				    vport->adapter->flags);
+	if (hr_reset_in_prog)
+		rtnl_lock();
 	idpf_vport_intr_napi_add_all(vport);
-
+	if (hr_reset_in_prog)
+		rtnl_unlock();
 	err = vport->adapter->dev_ops.reg_ops.intr_reg_init(vport);
 	if (err)
 		goto unroll_vectors_alloc;
-- 
2.46.0.76.ge559c4bf1a-goog