linux-kernel - Re: [PATCH v2] drm/panthor: Fix couple of NULL vs IS

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Message-ID: <20240402160756.1f767805@collabora.com>
Date: Tue, 2 Apr 2024 16:07:56 +0200
From: Boris Brezillon <boris.brezillon@...labora.com>
To: Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
Cc: Steven Price <steven.price@....com>, Liviu Dudau <liviu.dudau@....com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard
 <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, David Airlie
 <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, Heiko Stuebner
 <heiko@...ech.de>, Grant Likely <grant.likely@...aro.org>,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 dan.carpenter@...aro.org, kernel-janitors@...r.kernel.org,
 error27@...il.com
Subject: Re: [PATCH v2] drm/panthor: Fix couple of NULL vs IS_ERR() bugs

On Tue, 2 Apr 2024 19:35:41 +0530
Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com> wrote:

> Hi Boris,
> On 02/04/24 19:32, Boris Brezillon wrote:
> > On Tue,  2 Apr 2024 06:47:08 -0700
> > Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com> wrote:
> >   
> >> 1. The devm_drm_dev_alloc() function returns error pointers.
> >>     Update the error handling to check for error pointers instead of NULL.
> >> 2. Currently panthor_vm_get_heap_pool() returns both ERR_PTR() and
> >>     NULL(when create is false and if there is no poool attached to the
> >>     VM)
> >> 	- Change the function to return error pointers, when pool is
> >> 	  NULL return -ENOENT
> >> 	- Also handle the callers to check for IS_ERR() on failure.
> >>
> >> Fixes: 4bdca1150792 ("drm/panthor: Add the driver frontend block")
> >> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
> >> ---
> >> This is spotted by smatch and the patch is only compile tested
> >>
> >> v1->v2: Fix the function panthor_vm_get_heap_pool() to only return error
> >> pointers and handle the caller sites [Suggested by Boris Brezillon]
> >> 	- Also merge these IS_ERR() vs NULL bugs into same patch
> >> ---
> >>   drivers/gpu/drm/panthor/panthor_drv.c   | 6 +++---
> >>   drivers/gpu/drm/panthor/panthor_mmu.c   | 2 ++
> >>   drivers/gpu/drm/panthor/panthor_sched.c | 2 +-
> >>   3 files changed, 6 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/panthor/panthor_drv.c b/drivers/gpu/drm/panthor/panthor_drv.c
> >> index 11b3ccd58f85..c8374cd4a30d 100644
> >> --- a/drivers/gpu/drm/panthor/panthor_drv.c
> >> +++ b/drivers/gpu/drm/panthor/panthor_drv.c
> >> @@ -1090,8 +1090,8 @@ static int panthor_ioctl_tiler_heap_destroy(struct drm_device *ddev, void *data,
> >>   		return -EINVAL;
> >>   
> >>   	pool = panthor_vm_get_heap_pool(vm, false);
> >> -	if (!pool) {
> >> -		ret = -EINVAL;
> >> +	if (IS_ERR(pool)) {
> >> +		ret = PTR_ERR(pool);
> >>   		goto out_put_vm;
> >>   	}
> >>   
> >> @@ -1385,7 +1385,7 @@ static int panthor_probe(struct platform_device *pdev)
> >>   
> >>   	ptdev = devm_drm_dev_alloc(&pdev->dev, &panthor_drm_driver,
> >>   				   struct panthor_device, base);
> >> -	if (!ptdev)
> >> +	if (IS_ERR(ptdev))
> >>   		return -ENOMEM;
> >>     
> > 
> > Sorry, that one deserves a separate patch.
> >   
> 
> Ah okay, I was confused about the same.
> So I will send a V3 removing that part and could you please use the 
> independent patch that I sent before ?
> 
> https://lore.kernel.org/all/20240402104041.1689951-1-harshit.m.mogalapalli@oracle.com/

Yes, I already added my R-b on that one.