On 15.3.2016 22:40, Arnd Bergmann wrote:
> The qlt_check_reserve_free_req() function produces an incorrect warning
> when CONFIG_PROFILE_ANNOTATED_BRANCHES is set:
>
> drivers/scsi/qla2xxx/qla_target.c: In function 'qlt_check_reserve_free_req':
> drivers/scsi/qla2xxx/qla_target.c:1887:3: error: 'cnt_in' may be used
> uninitialized in this function [-Werror=maybe-uninitialized]
> ql_dbg(ql_dbg_io, vha, 0x305a,
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> "qla_target(%d): There is no room in the request ring:
> vha->req->ring_index=%d, vha->req->cnt=%d, req_cnt=%d Req-out=%d Req-in=%d
> Req-Length=%d\n",
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> vha->vp_idx, vha->req->ring_index,
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> vha->req->cnt, req_cnt, cnt, cnt_in, vha->req->length);
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/scsi/qla2xxx/qla_target.c:1887:3: error: 'cnt' may be used
> uninitialized in this function [-Werror=maybe-uninitialized]
>
> The problem is that gcc fails to track the state of the condition across
> an annotated branch.
>
> This slightly rearranges the code to move the second if() block
> into the first one, to avoid the warning while retaining the
> behavior of the code.
When the first 'if' is true the vha->req->ring_index gets a new value
assigned - so it could be possible that the second 'if' wont be true any more.
The code should not be merged into that single 'if', or am I missing something?
tomash
>
> Signed-off-by: Arnd Bergmann <a...@arndb.de>
> ---
> drivers/scsi/qla2xxx/qla_target.c | 16 +++++++++-------
> 1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/scsi/qla2xxx/qla_target.c
> b/drivers/scsi/qla2xxx/qla_target.c
> index 985231900aca..8a44d1541eb4 100644
> --- a/drivers/scsi/qla2xxx/qla_target.c
> +++ b/drivers/scsi/qla2xxx/qla_target.c
> @@ -1881,15 +1881,17 @@ static int qlt_check_reserve_free_req(struct
> scsi_qla_host *vha,
> else
> vha->req->cnt = vha->req->length -
> (vha->req->ring_index - cnt);
> - }
>
> - if (unlikely(vha->req->cnt < (req_cnt + 2))) {
> - ql_dbg(ql_dbg_io, vha, 0x305a,
> - "qla_target(%d): There is no room in the request ring:
> vha->req->ring_index=%d, vha->req->cnt=%d, req_cnt=%d Req-out=%d Req-in=%d
> Req-Length=%d\n",
> - vha->vp_idx, vha->req->ring_index,
> - vha->req->cnt, req_cnt, cnt, cnt_in, vha->req->length);
> - return -EAGAIN;
> + if (unlikely(vha->req->cnt < (req_cnt + 2))) {
> + ql_dbg(ql_dbg_io, vha, 0x305a,
> + "qla_target(%d): There is no room in the request
> ring: vha->req->ring_index=%d, vha->req->cnt=%d, req_cnt=%d Req-out=%d
> Req-in=%d Req-Length=%d\n",
> + vha->vp_idx, vha->req->ring_index,
> + vha->req->cnt, req_cnt, cnt, cnt_in,
> + vha->req->length);
> + return -EAGAIN;
> + }
> }
> +
> vha->req->cnt -= req_cnt;
>
> return 0;
--
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