linux-kernel - Re: [PATCH] scsi: qla4xxx: Don't call dma_free_coherent without dma_alloc

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Date:   Thu, 7 Mar 2019 10:49:17 -0800
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Nathan Chancellor <natechancellor@...il.com>
Cc:     QLogic-Storage-Upstream@...gic.com,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        linux-scsi@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        clang-built-linux@...glegroups.com
Subject: Re: [PATCH] scsi: qla4xxx: Don't call dma_free_coherent without dma_alloc_coherent

On Thu, Mar 7, 2019 at 10:41 AM Nathan Chancellor
<natechancellor@...il.com> wrote:
>
> When building with -Wsometimes-uninitialized, Clang warns:
>
> drivers/scsi/qla4xxx/ql4_os.c:5915:7: warning: variable 'buf_dma' is
> used uninitialized whenever 'if' condition is false
> [-Wsometimes-uninitialized]
>
> buf_dma is initialized by dma_alloc_coherent, which is only called in
> the middle conditional statement. Use that same conditional to call
> dma_free_coherent so that buf_dma is always initialized when used.
>
> Fixes: 2a991c215978 ("[SCSI] qla4xxx: Boot from SAN support for open-iscsi")
> Link: https://github.com/ClangBuiltLinux/linux/issues/391
> Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
> ---
>  drivers/scsi/qla4xxx/ql4_os.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/qla4xxx/ql4_os.c b/drivers/scsi/qla4xxx/ql4_os.c
> index 16a18d5d856f..88bb52456efd 100644
> --- a/drivers/scsi/qla4xxx/ql4_os.c
> +++ b/drivers/scsi/qla4xxx/ql4_os.c
> @@ -5982,7 +5982,8 @@ static int get_fw_boot_info(struct scsi_qla_host *ha, uint16_t ddb_index[])
>                           ddb_index[1]));
>
>  exit_boot_info_free:
> -       dma_free_coherent(&ha->pdev->dev, size, buf, buf_dma);
> +       if (is_qla80XX(ha))
> +               dma_free_coherent(&ha->pdev->dev, size, buf, buf_dma);

Very tricky code flow to follow in this function, but this patch makes
sense upon closer inspection.  Thanks for the patch Nathan
Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>

-- 
Thanks,
~Nick Desaulniers