Re: [PATCH] pci/switchtec: fix stream_open.cocci warnings (fwd)

Kirill Smelkov
2019-04-13T17:24:53Z

Hello everyone,

On Sat, Apr 13, 2019 at 06:50:57PM +0200, Julia Lawall wrote:
> Hello,
>
> Kirill will explain about this issue.

pci/switchtec switching to stream_open is already queued to merge
window and it was acked by Logan Gunthorpe:

https://lore.kernel.org/lkml/CAHk-=wgqgN5j1ZWnyVLqqoyU=CCWTYOko3MDyU8L_5e21KvHAg@mail.gmail.com/
https://lab.nexedi.com/kirr/linux/commit/edaeb4101860

( there are too many Cc's in that patch and email with it and reply-all to
it did not get into mailing list probably due to being considered as spam )

stream_open.cocci was issuing only warning for pci/switchtec, but after
8a29a3bae2a2 ("pci/switchtec: Don't use completion's wait queue") they
started to use wait_even_* inside read method and, since
stream_open.cocci considers wait_event_* as blocking the warning became
error. Previously it was completions there, but I added support for wait
events only for simplicity.

I can handle pci/switchtec switching via big nonseekable_open ->
stream_open change at next merge window, or, alternatively please feel
free to switch pci/switchtec now on its own. The change is correct - I
was manually reviewing all changes that stream_open.cocci produces and
pci/switchtec was there.

Kirill

> julia
>
> ---------- Forwarded message ----------
> Date: Sat, 13 Apr 2019 11:22:51 +0800
> From: kbuild test robot <lkp@intel.com>
> To: kbuild@01.org
> Cc: Julia Lawall <julia.lawall@lip6.fr>
> Subject: [PATCH] pci/switchtec: fix stream_open.cocci warnings
>
> CC: kbuild-all@01.org
> TO: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> CC: Kurt Schwemmer <kurt.schwemmer@microsemi.com>
> CC: Logan Gunthorpe <logang@deltatee.com>
> CC: Bjorn Helgaas <helgaas@kernel.org>
> CC: linux-pci@vger.kernel.org
> CC: linux-kernel@vger.kernel.org
>
> From: kbuild test robot <lkp@intel.com>
>
> drivers/pci/switch/switchtec.c:395:1-17: ERROR: switchtec_fops: .read() can deadlock .write(); change nonseekable_open -> stream_open to fix.
>
> Generated by: scripts/coccinelle/api/stream_open.cocci
>
> Fixes: 8a29a3bae2a2 ("pci/switchtec: Don't use completion's wait queue")
> Signed-off-by: kbuild test robot <lkp@intel.com>
> ---
>
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-5.0.y-rt-rebase
> head: 794c294ae4483c240429c25a0d18e272e92c94de
> commit: 8a29a3bae2a2dfb0116cd8791d9700515d6e765e [154/311] pci/switchtec: Don't use completion's wait queue
> :::::: branch date: 7 hours ago
> :::::: commit date: 7 hours ago
>
> Please take the patch only if it's a positive warning. Thanks!
>
> switchtec.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- a/drivers/pci/switch/switchtec.c
> +++ b/drivers/pci/switch/switchtec.c
> @@ -392,7 +392,7 @@ static int switchtec_dev_open(struct ino
> return PTR_ERR(stuser);
>
> filp->private_data = stuser;
> - nonseekable_open(inode, filp);
> + stream_open(inode, filp);
>
> dev_dbg(&stdev->dev, "%s: %p\n", __func__, stuser);