Re: [PATCH net] net/smc: Fix memory leak when using percpu refs

[Wenjia Zhang <wenjia@linux.ibm.com>]

On 10.10.24 13:56, Kai Shen wrote:
> This patch adds missing percpu_ref_exit when releasing percpu refs.
> When releasing percpu refs, percpu_ref_exit should be called.
> Otherwise, memory leak happens.
> 
> Fixes: 79a22238b4f2 ("net/smc: Use percpu ref for wr tx reference")
> Signed-off-by: Kai Shen <KaiShen@linux.alibaba.com>
> ---
>   net/smc/smc_wr.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/net/smc/smc_wr.c b/net/smc/smc_wr.c
> index 0021065a600a..994c0cd4fddb 100644
> --- a/net/smc/smc_wr.c
> +++ b/net/smc/smc_wr.c
> @@ -648,8 +648,10 @@ void smc_wr_free_link(struct smc_link *lnk)
>   	smc_wr_tx_wait_no_pending_sends(lnk);
>   	percpu_ref_kill(&lnk->wr_reg_refs);
>   	wait_for_completion(&lnk->reg_ref_comp);
> +	percpu_ref_exit(&lnk->wr_reg_refs);
>   	percpu_ref_kill(&lnk->wr_tx_refs);
>   	wait_for_completion(&lnk->tx_ref_comp);
> +	percpu_ref_exit(&lnk->wr_tx_refs);
>   
>   	if (lnk->wr_rx_dma_addr) {
>   		ib_dma_unmap_single(ibdev, lnk->wr_rx_dma_addr,
> @@ -912,11 +914,13 @@ int smc_wr_create_link(struct smc_link *lnk)
>   	init_waitqueue_head(&lnk->wr_reg_wait);
>   	rc = percpu_ref_init(&lnk->wr_reg_refs, smcr_wr_reg_refs_free, 0, GFP_KERNEL);
>   	if (rc)
> -		goto dma_unmap;
> +		goto cancel_ref;
>   	init_completion(&lnk->reg_ref_comp);
>   	init_waitqueue_head(&lnk->wr_rx_empty_wait);
>   	return rc;
>   
> +cancel_ref:
> +	percpu_ref_exit(&lnk->wr_tx_refs);
>   dma_unmap:
>   	if (lnk->wr_rx_v2_dma_addr) {
>   		ib_dma_unmap_single(ibdev, lnk->wr_rx_v2_dma_addr,

It looks reasonable to me. Thanks for the fix!
Reviewed-by: Wenjia Zhang <wenjia@linux.ibm.com>

Thanks,
Wenjia