Re: [PATCH for-next v2] RDMA/cma: Replace RMW with atomic bit-ops

[Leon Romanovsky <leon@kernel.org>]

On Thu, Jun 17, 2021 at 02:59:25PM +0200, Håkon Bugge wrote:
> The struct rdma_id_private contains three bit-fields, tos_set,
> timeout_set, and min_rnr_timer_set. These are set by accessor
> functions without any synchronization. If two or all accessor
> functions are invoked in close proximity in time, there will be
> Read-Modify-Write from several contexts to the same variable, and the
> result will be intermittent.
> 
> Replace with a flag variable and an inline function for set with
> appropriate memory barriers and the use of test_bit().
> 
> Signed-off-by: Håkon Bugge <haakon.bugge@oracle.com>
> Signed-off-by: Hans Westgaard Ry<hans.westgaard.ry@oracle.com>
> 
> ---
> 	v1 -> v2:
> 	   * Removed define wizardry and replaced with a set function
>              with memory barriers. Suggested by Leon.
> 	   * Removed zero-initialization of flags, due to kzalloc(),
>              as suggested by Leon
> 	   * Review comments from Stefan implicitly adapted due to
>              first bullet above
> 	   * Moved defines and inline function from header file to
>              cma.c, as suggested by the undersigned
> 	   * Renamed enum to cm_id_priv_flag_bits as suggested by the
>              undersigned
> ---
>  drivers/infiniband/core/cma.c      | 38 +++++++++++++++++++++++++-------------
>  drivers/infiniband/core/cma_priv.h |  4 +---
>  2 files changed, 26 insertions(+), 16 deletions(-)

This patch generates checkpatch warnings.

➜  kernel git:(rdma-next) git checkpatch
WARNING: line length of 86 exceeds 80 columns
#69: FILE: drivers/infiniband/core/cma.c:1149:
+	if ((*qp_attr_mask & IB_QP_TIMEOUT) && test_bit(TIMEOUT_SET, &id_priv->flags))

WARNING: line length of 98 exceeds 80 columns
#73: FILE: drivers/infiniband/core/cma.c:1152:
+	if ((*qp_attr_mask & IB_QP_MIN_RNR_TIMER) && test_bit(MIN_RNR_TIMER_SET, &id_priv->flags))

WARNING: line length of 86 exceeds 80 columns
#127: FILE: drivers/infiniband/core/cma.c:3048:
+	u8 tos = test_bit(TOS_SET, &id_priv->flags) ? id_priv->tos : default_roce_tos;

WARNING: line length of 84 exceeds 80 columns
#136: FILE: drivers/infiniband/core/cma.c:3096:
+	route->path_rec->packet_life_time = test_bit(TIMEOUT_SET, &id_priv->flags) ?

0001-RDMA-cma-Replace-RMW-with-atomic-bit-ops.patch total: 0 errors, 4 warnings, 118 lines checked

Thanks