net/mlx5: Serialize firmware reset with devlink

The firmware reset mechanism can be triggered by asynchronous events,
which may race with other devlink operations like devlink reload or
devlink dev eswitch set, potentially leading to inconsistent states.

This patch addresses the race by using the devl_lock to serialize the
firmware reset against other devlink operations. When a reset is
requested, the driver attempts to acquire the lock. If successful, it
sets a flag to block devlink reload or eswitch changes, ACKs the reset
to firmware and then releases the lock. If the lock is already held by
another operation, the driver NACKs the firmware reset request,
indicating that the reset cannot proceed.

Firmware reset does not keep the devl_lock and instead uses an internal
firmware reset bit. This is because firmware resets can be triggered by
asynchronous events, and processed in different threads. It is illegal
and unsafe to acquire a lock in one thread and attempt to release it in
another, as lock ownership is intrinsically thread-specific.

This change ensures that firmware resets and other devlink operations
are mutually exclusive during the critical reset request phase,
preventing race conditions.

Fixes: 38b9f903f22b ("net/mlx5: Handle sync reset request event")
Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Mateusz Berezecki <mberezecki@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/1765284977-1363052-6-git-send-email-tariqt@nvidia.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

0 files changed, 0 insertions, 0 deletions