Re: [PATCH for-next 1/9] RDMA/rxe: Fix handling sleepable in rxe_pool.c

[Jason Gunthorpe <jgg@nvidia.com>]

On Fri, Jul 21, 2023 at 03:50:14PM -0500, Bob Pearson wrote:
> Since the AH creation and destroy verbs APIs can be called in
> interrupt context it is necessary to not sleep in these cases.
> This was partially dealt with in previous fixes but some cases
> remain where the code could still potentially sleep.
> 
> This patch fixes this by extending the __rxe_finalize() call to
> have a sleepable parameter and using this in the AH verbs calls.
> It also fixes one call to rxe_cleanup which did not use the
> sleepable API.
> 
> Fixes: 215d0a755e1b ("RDMA/rxe: Stop lookup of partially built objects")
> Signed-off-by: Bob Pearson <rpearsonhpe@gmail.com>
> ---
>  drivers/infiniband/sw/rxe/rxe_pool.c  |  5 +++--
>  drivers/infiniband/sw/rxe/rxe_pool.h  |  5 +++--
>  drivers/infiniband/sw/rxe/rxe_verbs.c | 11 ++++++-----
>  3 files changed, 12 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/infiniband/sw/rxe/rxe_pool.c b/drivers/infiniband/sw/rxe/rxe_pool.c
> index 6215c6de3a84..de0043b6d3f3 100644
> --- a/drivers/infiniband/sw/rxe/rxe_pool.c
> +++ b/drivers/infiniband/sw/rxe/rxe_pool.c
> @@ -247,10 +247,11 @@ int __rxe_put(struct rxe_pool_elem *elem)
>  	return kref_put(&elem->ref_cnt, rxe_elem_release);
>  }
>  
> -void __rxe_finalize(struct rxe_pool_elem *elem)
> +void __rxe_finalize(struct rxe_pool_elem *elem, bool sleepable)
>  {
>  	void *xa_ret;
> +	gfp_t gfp_flags = sleepable ? GFP_KERNEL : GFP_ATOMIC;
>  
> -	xa_ret = xa_store(&elem->pool->xa, elem->index, elem, GFP_KERNEL);
> +	xa_ret = xa_store(&elem->pool->xa, elem->index, elem, gfp_flags);
>  	WARN_ON(xa_err(xa_ret));
>  }

You don't need to do this, there is no allocation here, when you call
xa_alloc_cyclic() it reserved all the memory necessary for this.

Just add a comment and mark it GFP_ATOMIC.

Jason