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* [PATCH] fs: io_uring: remove NULL check before kfree
@ 2022-06-14  9:13 Dongliang Mu
  2022-06-14  9:26 ` Muchun Song
  0 siblings, 1 reply; 3+ messages in thread
From: Dongliang Mu @ 2022-06-14  9:13 UTC (permalink / raw)
  To: Jens Axboe, Pavel Begunkov; +Cc: mudongliang, io-uring, linux-kernel

From: mudongliang <[email protected]>

kfree can handle NULL pointer as its argument.
According to coccinelle isnullfree check, remove NULL check
before kfree operation.

Signed-off-by: mudongliang <[email protected]>
---
 fs/io_uring.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 3aab4182fd89..bec47eae2a9b 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -3159,8 +3159,7 @@ static void io_free_batch_list(struct io_ring_ctx *ctx,
 			if ((req->flags & REQ_F_POLLED) && req->apoll) {
 				struct async_poll *apoll = req->apoll;
 
-				if (apoll->double_poll)
-					kfree(apoll->double_poll);
+				kfree(apoll->double_poll);
 				list_add(&apoll->poll.wait.entry,
 						&ctx->apoll_cache);
 				req->flags &= ~REQ_F_POLLED;
@@ -4499,8 +4498,7 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags)
 	kiocb_done(req, ret, issue_flags);
 out_free:
 	/* it's faster to check here then delegate to kfree */
-	if (iovec)
-		kfree(iovec);
+	kfree(iovec);
 	return 0;
 }
 
@@ -4602,8 +4600,7 @@ static int io_write(struct io_kiocb *req, unsigned int issue_flags)
 	}
 out_free:
 	/* it's reportedly faster than delegating the null check to kfree() */
-	if (iovec)
-		kfree(iovec);
+	kfree(iovec);
 	return ret;
 }
 
@@ -6227,8 +6224,7 @@ static int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags)
 		req_set_fail(req);
 	}
 	/* fast path, check for non-NULL to avoid function call */
-	if (kmsg->free_iov)
-		kfree(kmsg->free_iov);
+	kfree(kmsg->free_iov);
 	req->flags &= ~REQ_F_NEED_CLEANUP;
 	if (ret >= 0)
 		ret += sr->done_io;
@@ -6481,8 +6477,7 @@ static int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
 	}
 
 	/* fast path, check for non-NULL to avoid function call */
-	if (kmsg->free_iov)
-		kfree(kmsg->free_iov);
+	kfree(kmsg->free_iov);
 	req->flags &= ~REQ_F_NEED_CLEANUP;
 	if (ret >= 0)
 		ret += sr->done_io;
-- 
2.35.1


^ permalink raw reply related	[flat|nested] 3+ messages in thread

* Re: [PATCH] fs: io_uring: remove NULL check before kfree
  2022-06-14  9:13 [PATCH] fs: io_uring: remove NULL check before kfree Dongliang Mu
@ 2022-06-14  9:26 ` Muchun Song
  2022-06-14  9:29   ` Dongliang Mu
  0 siblings, 1 reply; 3+ messages in thread
From: Muchun Song @ 2022-06-14  9:26 UTC (permalink / raw)
  To: Dongliang Mu; +Cc: Jens Axboe, Pavel Begunkov, mudongliang, io-uring, LKML

On Tue, Jun 14, 2022 at 5:14 PM Dongliang Mu <[email protected]> wrote:
>
> From: mudongliang <[email protected]>
>
> kfree can handle NULL pointer as its argument.
> According to coccinelle isnullfree check, remove NULL check
> before kfree operation.
>
> Signed-off-by: mudongliang <[email protected]>
> ---
>  fs/io_uring.c | 15 +++++----------
>  1 file changed, 5 insertions(+), 10 deletions(-)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 3aab4182fd89..bec47eae2a9b 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -3159,8 +3159,7 @@ static void io_free_batch_list(struct io_ring_ctx *ctx,
>                         if ((req->flags & REQ_F_POLLED) && req->apoll) {
>                                 struct async_poll *apoll = req->apoll;
>
> -                               if (apoll->double_poll)
> -                                       kfree(apoll->double_poll);
> +                               kfree(apoll->double_poll);
>                                 list_add(&apoll->poll.wait.entry,
>                                                 &ctx->apoll_cache);
>                                 req->flags &= ~REQ_F_POLLED;
> @@ -4499,8 +4498,7 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags)
>         kiocb_done(req, ret, issue_flags);
>  out_free:
>         /* it's faster to check here then delegate to kfree */

I am feeling you are not on the right way. See the comment
here.

Thanks.

> -       if (iovec)
> -               kfree(iovec);
> +       kfree(iovec);
>         return 0;
>  }
>
> @@ -4602,8 +4600,7 @@ static int io_write(struct io_kiocb *req, unsigned int issue_flags)
>         }
>  out_free:
>         /* it's reportedly faster than delegating the null check to kfree() */

See here.

> -       if (iovec)
> -               kfree(iovec);
> +       kfree(iovec);
>         return ret;
>  }
>
> @@ -6227,8 +6224,7 @@ static int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags)
>                 req_set_fail(req);
>         }
>         /* fast path, check for non-NULL to avoid function call */

here.

> -       if (kmsg->free_iov)
> -               kfree(kmsg->free_iov);
> +       kfree(kmsg->free_iov);
>         req->flags &= ~REQ_F_NEED_CLEANUP;
>         if (ret >= 0)
>                 ret += sr->done_io;
> @@ -6481,8 +6477,7 @@ static int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
>         }
>
>         /* fast path, check for non-NULL to avoid function call */

And here.

> -       if (kmsg->free_iov)
> -               kfree(kmsg->free_iov);
> +       kfree(kmsg->free_iov);
>         req->flags &= ~REQ_F_NEED_CLEANUP;
>         if (ret >= 0)
>                 ret += sr->done_io;
> --
> 2.35.1
>

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] fs: io_uring: remove NULL check before kfree
  2022-06-14  9:26 ` Muchun Song
@ 2022-06-14  9:29   ` Dongliang Mu
  0 siblings, 0 replies; 3+ messages in thread
From: Dongliang Mu @ 2022-06-14  9:29 UTC (permalink / raw)
  To: Muchun Song; +Cc: Dongliang Mu, Jens Axboe, Pavel Begunkov, io-uring, LKML

On Tue, Jun 14, 2022 at 5:26 PM Muchun Song <[email protected]> wrote:
>
> On Tue, Jun 14, 2022 at 5:14 PM Dongliang Mu <[email protected]> wrote:
> >
> > From: mudongliang <[email protected]>
> >
> > kfree can handle NULL pointer as its argument.
> > According to coccinelle isnullfree check, remove NULL check
> > before kfree operation.
> >
> > Signed-off-by: mudongliang <[email protected]>
> > ---
> >  fs/io_uring.c | 15 +++++----------
> >  1 file changed, 5 insertions(+), 10 deletions(-)
> >
> > diff --git a/fs/io_uring.c b/fs/io_uring.c
> > index 3aab4182fd89..bec47eae2a9b 100644
> > --- a/fs/io_uring.c
> > +++ b/fs/io_uring.c
> > @@ -3159,8 +3159,7 @@ static void io_free_batch_list(struct io_ring_ctx *ctx,
> >                         if ((req->flags & REQ_F_POLLED) && req->apoll) {
> >                                 struct async_poll *apoll = req->apoll;
> >
> > -                               if (apoll->double_poll)
> > -                                       kfree(apoll->double_poll);
> > +                               kfree(apoll->double_poll);
> >                                 list_add(&apoll->poll.wait.entry,
> >                                                 &ctx->apoll_cache);
> >                                 req->flags &= ~REQ_F_POLLED;
> > @@ -4499,8 +4498,7 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags)
> >         kiocb_done(req, ret, issue_flags);
> >  out_free:
> >         /* it's faster to check here then delegate to kfree */
>
> I am feeling you are not on the right way. See the comment
> here.

Thanks for your reply. I ignore them previously. Any method to make
coccicheck ignore such cases?

>
> Thanks.
>
> > -       if (iovec)
> > -               kfree(iovec);
> > +       kfree(iovec);
> >         return 0;
> >  }
> >
> > @@ -4602,8 +4600,7 @@ static int io_write(struct io_kiocb *req, unsigned int issue_flags)
> >         }
> >  out_free:
> >         /* it's reportedly faster than delegating the null check to kfree() */
>
> See here.
>
> > -       if (iovec)
> > -               kfree(iovec);
> > +       kfree(iovec);
> >         return ret;
> >  }
> >
> > @@ -6227,8 +6224,7 @@ static int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags)
> >                 req_set_fail(req);
> >         }
> >         /* fast path, check for non-NULL to avoid function call */
>
> here.
>
> > -       if (kmsg->free_iov)
> > -               kfree(kmsg->free_iov);
> > +       kfree(kmsg->free_iov);
> >         req->flags &= ~REQ_F_NEED_CLEANUP;
> >         if (ret >= 0)
> >                 ret += sr->done_io;
> > @@ -6481,8 +6477,7 @@ static int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
> >         }
> >
> >         /* fast path, check for non-NULL to avoid function call */
>
> And here.
>
> > -       if (kmsg->free_iov)
> > -               kfree(kmsg->free_iov);
> > +       kfree(kmsg->free_iov);
> >         req->flags &= ~REQ_F_NEED_CLEANUP;
> >         if (ret >= 0)
> >                 ret += sr->done_io;
> > --
> > 2.35.1
> >

^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2022-06-14  9:29 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
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2022-06-14  9:13 [PATCH] fs: io_uring: remove NULL check before kfree Dongliang Mu
2022-06-14  9:26 ` Muchun Song
2022-06-14  9:29   ` Dongliang Mu

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