6.8-stable review patch. If anyone has any objections, please let me know.
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From: Ido Schimmel idosch@nvidia.com
[ Upstream commit d90cfe20562407d9f080d24123078d666d730707 ]
The purpose of the rehash delayed work is to reduce the number of masks (eRPs) used by an ACL region as the eRP bank is a global and limited resource.
This is done in three steps:
1. Creating a new set of masks and a new ACL region which will use the new masks and to which the existing filters will be migrated to. The new region is assigned to 'vregion->region' and the region from which the filters are migrated from is assigned to 'vregion->region2'.
2. Migrating all the filters from the old region to the new region.
3. Destroying the old region and setting 'vregion->region2' to NULL.
Only the second steps is performed under the 'vregion->lock' mutex although its comments says that among other things it "Protects consistency of region, region2 pointers".
This is problematic as the first step can race with filter insertion from user space that uses 'vregion->region', but under the mutex.
Fix by holding the mutex across the entirety of the delayed work and not only during the second step.
Fixes: 2bffc5322fd8 ("mlxsw: spectrum_acl: Don't take mutex in mlxsw_sp_acl_tcam_vregion_rehash_work()") Signed-off-by: Ido Schimmel idosch@nvidia.com Tested-by: Alexander Zubkov green@qrator.net Reviewed-by: Petr Machata petrm@nvidia.com Signed-off-by: Petr Machata petrm@nvidia.com Reviewed-by: Simon Horman horms@kernel.org Link: https://lore.kernel.org/r/1ec1d54edf2bad0a369e6b4fa030aba64e1f124b.171379710... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_tcam.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_tcam.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_tcam.c index b6a4652a6475a..9c0c728bb42dc 100644 --- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_tcam.c +++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_tcam.c @@ -718,7 +718,9 @@ static void mlxsw_sp_acl_tcam_vregion_rehash_work(struct work_struct *work) rehash.dw.work); int credits = MLXSW_SP_ACL_TCAM_VREGION_REHASH_CREDITS;
+ mutex_lock(&vregion->lock); mlxsw_sp_acl_tcam_vregion_rehash(vregion->mlxsw_sp, vregion, &credits); + mutex_unlock(&vregion->lock); if (credits < 0) /* Rehash gone out of credits so it was interrupted. * Schedule the work as soon as possible to continue. @@ -1323,7 +1325,6 @@ mlxsw_sp_acl_tcam_vregion_migrate(struct mlxsw_sp *mlxsw_sp, int err, err2;
trace_mlxsw_sp_acl_tcam_vregion_migrate(mlxsw_sp, vregion); - mutex_lock(&vregion->lock); err = mlxsw_sp_acl_tcam_vchunk_migrate_all(mlxsw_sp, vregion, ctx, credits); if (err) { @@ -1343,7 +1344,6 @@ mlxsw_sp_acl_tcam_vregion_migrate(struct mlxsw_sp *mlxsw_sp, /* Let the rollback to be continued later on. */ } } - mutex_unlock(&vregion->lock); trace_mlxsw_sp_acl_tcam_vregion_migrate_end(mlxsw_sp, vregion); return err; }