diff mbox series

xprtrdma: Fix a maybe-uninitialized compiler warning

Message ID 2b32d41cf6a502918a685447cd749c4b1cb0d16d.1635685588.git.bcodding@redhat.com (mailing list archive)
State New, archived
Headers show
Series xprtrdma: Fix a maybe-uninitialized compiler warning | expand

Commit Message

Benjamin Coddington Oct. 31, 2021, 1:08 p.m. UTC
This minor fix-up keeps GCC from complaining that "last' may be used
uninitialized", which breaks some build workflows that have been running
with all warnings treated as errors.

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
---
 net/sunrpc/xprtrdma/frwr_ops.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Chuck Lever Oct. 31, 2021, 3:04 p.m. UTC | #1
> On Oct 31, 2021, at 9:08 AM, Benjamin Coddington <bcodding@redhat.com> wrote:
> 
> This minor fix-up keeps GCC from complaining that "last' may be used
> uninitialized", which breaks some build workflows that have been running
> with all warnings treated as errors.
> 
> Signed-off-by: Benjamin Coddington <bcodding@redhat.com>

Reviewed-by: Chuck Lever <chuck.lever@oracle.com>


> ---
> net/sunrpc/xprtrdma/frwr_ops.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/sunrpc/xprtrdma/frwr_ops.c b/net/sunrpc/xprtrdma/frwr_ops.c
> index f700b34a5bfd..de813fa07daa 100644
> --- a/net/sunrpc/xprtrdma/frwr_ops.c
> +++ b/net/sunrpc/xprtrdma/frwr_ops.c
> @@ -503,7 +503,7 @@ static void frwr_wc_localinv_wake(struct ib_cq *cq, struct ib_wc *wc)
>  */
> void frwr_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
> {
> -	struct ib_send_wr *first, **prev, *last;
> +	struct ib_send_wr *first, **prev, *last = NULL;
> 	struct rpcrdma_ep *ep = r_xprt->rx_ep;
> 	const struct ib_send_wr *bad_wr;
> 	struct rpcrdma_mr *mr;
> @@ -608,7 +608,7 @@ static void frwr_wc_localinv_done(struct ib_cq *cq, struct ib_wc *wc)
>  */
> void frwr_unmap_async(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
> {
> -	struct ib_send_wr *first, *last, **prev;
> +	struct ib_send_wr *first, *last = NULL, **prev;
> 	struct rpcrdma_ep *ep = r_xprt->rx_ep;
> 	struct rpcrdma_mr *mr;
> 	int rc;
> -- 
> 2.31.1
> 

--
Chuck Lever
Trond Myklebust Nov. 2, 2021, 4:43 p.m. UTC | #2
On Sun, 2021-10-31 at 15:04 +0000, Chuck Lever III wrote:
> 
> 
> > On Oct 31, 2021, at 9:08 AM, Benjamin Coddington
> > <bcodding@redhat.com> wrote:
> > 
> > This minor fix-up keeps GCC from complaining that "last' may be used
> > uninitialized", which breaks some build workflows that have been
> > running
> > with all warnings treated as errors.
> > 
> > Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
> 
> Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
> 
> 
> > ---
> > net/sunrpc/xprtrdma/frwr_ops.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/net/sunrpc/xprtrdma/frwr_ops.c
> > b/net/sunrpc/xprtrdma/frwr_ops.c
> > index f700b34a5bfd..de813fa07daa 100644
> > --- a/net/sunrpc/xprtrdma/frwr_ops.c
> > +++ b/net/sunrpc/xprtrdma/frwr_ops.c
> > @@ -503,7 +503,7 @@ static void frwr_wc_localinv_wake(struct ib_cq
> > *cq, struct ib_wc *wc)
> >  */
> > void frwr_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req
> > *req)
> > {
> > -       struct ib_send_wr *first, **prev, *last;
> > +       struct ib_send_wr *first, **prev, *last = NULL;
> >         struct rpcrdma_ep *ep = r_xprt->rx_ep;
> >         const struct ib_send_wr *bad_wr;
> >         struct rpcrdma_mr *mr;

Err... Definitely not sufficient.

gcc is absolutely correct to complain here, because if req-
>rl_registered is empty, then the whole rest of the function after that
while() loop is invalid.

> > @@ -608,7 +608,7 @@ static void frwr_wc_localinv_done(struct ib_cq
> > *cq, struct ib_wc *wc)
> >  */
> > void frwr_unmap_async(struct rpcrdma_xprt *r_xprt, struct
> > rpcrdma_req *req)
> > {
> > -       struct ib_send_wr *first, *last, **prev;
> > +       struct ib_send_wr *first, *last = NULL, **prev;
> >         struct rpcrdma_ep *ep = r_xprt->rx_ep;
> >         struct rpcrdma_mr *mr;
> >         int rc;
> > -- 
> > 2.31.1
> > 

Ditto.
Chuck Lever Nov. 2, 2021, 4:50 p.m. UTC | #3
> On Nov 2, 2021, at 12:43 PM, Trond Myklebust <trondmy@hammerspace.com> wrote:
> 
> On Sun, 2021-10-31 at 15:04 +0000, Chuck Lever III wrote:
>> 
>> 
>>> On Oct 31, 2021, at 9:08 AM, Benjamin Coddington
>>> <bcodding@redhat.com> wrote:
>>> 
>>> This minor fix-up keeps GCC from complaining that "last' may be used
>>> uninitialized", which breaks some build workflows that have been
>>> running
>>> with all warnings treated as errors.
>>> 
>>> Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
>> 
>> Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
>> 
>> 
>>> ---
>>> net/sunrpc/xprtrdma/frwr_ops.c | 4 ++--
>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>> 
>>> diff --git a/net/sunrpc/xprtrdma/frwr_ops.c
>>> b/net/sunrpc/xprtrdma/frwr_ops.c
>>> index f700b34a5bfd..de813fa07daa 100644
>>> --- a/net/sunrpc/xprtrdma/frwr_ops.c
>>> +++ b/net/sunrpc/xprtrdma/frwr_ops.c
>>> @@ -503,7 +503,7 @@ static void frwr_wc_localinv_wake(struct ib_cq
>>> *cq, struct ib_wc *wc)
>>>  */
>>> void frwr_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req
>>> *req)
>>> {
>>> -       struct ib_send_wr *first, **prev, *last;
>>> +       struct ib_send_wr *first, **prev, *last = NULL;
>>>         struct rpcrdma_ep *ep = r_xprt->rx_ep;
>>>         const struct ib_send_wr *bad_wr;
>>>         struct rpcrdma_mr *mr;
> 
> Err... Definitely not sufficient.
> 
> gcc is absolutely correct to complain here, because if req-
>> rl_registered is empty, then the whole rest of the function after that
> while() loop is invalid.

The callers ensure rl_registered is not empty.

This used to be preferred: don't add code to check conditions
that are known to be true. If that policy is different now,
then yes, this code will have to be restructured.


>>> @@ -608,7 +608,7 @@ static void frwr_wc_localinv_done(struct ib_cq
>>> *cq, struct ib_wc *wc)
>>>  */
>>> void frwr_unmap_async(struct rpcrdma_xprt *r_xprt, struct
>>> rpcrdma_req *req)
>>> {
>>> -       struct ib_send_wr *first, *last, **prev;
>>> +       struct ib_send_wr *first, *last = NULL, **prev;
>>>         struct rpcrdma_ep *ep = r_xprt->rx_ep;
>>>         struct rpcrdma_mr *mr;
>>>         int rc;
>>> -- 
>>> 2.31.1
>>> 
> 
> Ditto.
> 
> -- 
> Trond Myklebust
> Linux NFS client maintainer, Hammerspace
> trond.myklebust@hammerspace.com

--
Chuck Lever
Trond Myklebust Nov. 2, 2021, 5:36 p.m. UTC | #4
On Tue, 2021-11-02 at 16:50 +0000, Chuck Lever III wrote:
> 
> 
> > On Nov 2, 2021, at 12:43 PM, Trond Myklebust
> > <trondmy@hammerspace.com> wrote:
> > 
> > On Sun, 2021-10-31 at 15:04 +0000, Chuck Lever III wrote:
> > > 
> > > 
> > > > On Oct 31, 2021, at 9:08 AM, Benjamin Coddington
> > > > <bcodding@redhat.com> wrote:
> > > > 
> > > > This minor fix-up keeps GCC from complaining that "last' may be
> > > > used
> > > > uninitialized", which breaks some build workflows that have
> > > > been
> > > > running
> > > > with all warnings treated as errors.
> > > > 
> > > > Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
> > > 
> > > Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
> > > 
> > > 
> > > > ---
> > > > net/sunrpc/xprtrdma/frwr_ops.c | 4 ++--
> > > > 1 file changed, 2 insertions(+), 2 deletions(-)
> > > > 
> > > > diff --git a/net/sunrpc/xprtrdma/frwr_ops.c
> > > > b/net/sunrpc/xprtrdma/frwr_ops.c
> > > > index f700b34a5bfd..de813fa07daa 100644
> > > > --- a/net/sunrpc/xprtrdma/frwr_ops.c
> > > > +++ b/net/sunrpc/xprtrdma/frwr_ops.c
> > > > @@ -503,7 +503,7 @@ static void frwr_wc_localinv_wake(struct
> > > > ib_cq
> > > > *cq, struct ib_wc *wc)
> > > >  */
> > > > void frwr_unmap_sync(struct rpcrdma_xprt *r_xprt, struct
> > > > rpcrdma_req
> > > > *req)
> > > > {
> > > > -       struct ib_send_wr *first, **prev, *last;
> > > > +       struct ib_send_wr *first, **prev, *last = NULL;
> > > >         struct rpcrdma_ep *ep = r_xprt->rx_ep;
> > > >         const struct ib_send_wr *bad_wr;
> > > >         struct rpcrdma_mr *mr;
> > 
> > Err... Definitely not sufficient.
> > 
> > gcc is absolutely correct to complain here, because if req-
> > > rl_registered is empty, then the whole rest of the function after
> > > that
> > while() loop is invalid.
> 
> The callers ensure rl_registered is not empty.
> 
> This used to be preferred: don't add code to check conditions
> that are known to be true. If that policy is different now,
> then yes, this code will have to be restructured.
> 

If that's the case, then please change those two "while() {}" blocks
into "do { } while();" so that we avoid the apparently unnecessary
first check for whether the list is empty. That would be the real fix
here, and one that clearly documents the expectation.

> 
> > > > @@ -608,7 +608,7 @@ static void frwr_wc_localinv_done(struct
> > > > ib_cq
> > > > *cq, struct ib_wc *wc)
> > > >  */
> > > > void frwr_unmap_async(struct rpcrdma_xprt *r_xprt, struct
> > > > rpcrdma_req *req)
> > > > {
> > > > -       struct ib_send_wr *first, *last, **prev;
> > > > +       struct ib_send_wr *first, *last = NULL, **prev;
> > > >         struct rpcrdma_ep *ep = r_xprt->rx_ep;
> > > >         struct rpcrdma_mr *mr;
> > > >         int rc;
> > > > -- 
> > > > 2.31.1
> > > > 
> > 
> > Ditto.
> > 
> > -- 
> > Trond Myklebust
> > Linux NFS client maintainer, Hammerspace
> > trond.myklebust@hammerspace.com
> 
> --
> Chuck Lever
> 
> 
>
diff mbox series

Patch

diff --git a/net/sunrpc/xprtrdma/frwr_ops.c b/net/sunrpc/xprtrdma/frwr_ops.c
index f700b34a5bfd..de813fa07daa 100644
--- a/net/sunrpc/xprtrdma/frwr_ops.c
+++ b/net/sunrpc/xprtrdma/frwr_ops.c
@@ -503,7 +503,7 @@  static void frwr_wc_localinv_wake(struct ib_cq *cq, struct ib_wc *wc)
  */
 void frwr_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
 {
-	struct ib_send_wr *first, **prev, *last;
+	struct ib_send_wr *first, **prev, *last = NULL;
 	struct rpcrdma_ep *ep = r_xprt->rx_ep;
 	const struct ib_send_wr *bad_wr;
 	struct rpcrdma_mr *mr;
@@ -608,7 +608,7 @@  static void frwr_wc_localinv_done(struct ib_cq *cq, struct ib_wc *wc)
  */
 void frwr_unmap_async(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
 {
-	struct ib_send_wr *first, *last, **prev;
+	struct ib_send_wr *first, *last = NULL, **prev;
 	struct rpcrdma_ep *ep = r_xprt->rx_ep;
 	struct rpcrdma_mr *mr;
 	int rc;