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Tue, 22 Sep 2026 00:22:52 -0700 (PDT) Date: Tue, 22 Sep 2026 10:22:48 +0300 From: Dan Carpenter To: Lucas Costa <2000.costalucas@gmail.com> Cc: Sudip Mukherjee , Teddy Wang , Greg Kroah-Hartman , linux-fbdev@vger.kernel.org, linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH] staging: sm750fb: free cmap on framebuffer release Message-ID: References: <20260922035302.167378-1-2000.costalucas@gmail.com> Precedence: bulk X-Mailing-List: linux-staging@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260922035302.167378-1-2000.costalucas@gmail.com> On Tue, Sep 22, 2026 at 12:53:02AM -0300, Lucas Costa wrote: > The driver never calls fb_dealloc_cmap() after it has been allocated, > so when the buffer is torn down we leak. > > This happens on every unbind, and when an error is detected in > sm750fb_framebuffer_alloc(). > > fb_dealloc_cmap() gets called before framebuffer_release() in both places. > > Fixes: 81dee67e215b ("staging: sm750fb: add sm750 to staging") > > Signed-off-by: Lucas Costa <2000.costalucas@gmail.com> > --- > drivers/staging/sm750fb/sm750.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/staging/sm750fb/sm750.c b/drivers/staging/sm750fb/sm750.c > index 8b93bfeb217b..92412534239c 100644 > --- a/drivers/staging/sm750fb/sm750.c > +++ b/drivers/staging/sm750fb/sm750.c > @@ -910,6 +910,7 @@ static void sm750fb_framebuffer_release(struct sm750_dev *sm750_dev) > while (sm750_dev->fb_count) { > fb_info = sm750_dev->fbinfo[sm750_dev->fb_count - 1]; > unregister_framebuffer(fb_info); > + fb_dealloc_cmap(&fb_info->cmap); > framebuffer_release(fb_info); > sm750_dev->fb_count--; > } > @@ -943,6 +944,7 @@ static int sm750fb_framebuffer_alloc(struct sm750_dev *sm750_dev, int fbidx) > return 0; > > release_fb: > + fb_dealloc_cmap(&fb_info->cmap); > framebuffer_release(fb_info); > return err; This works, but I don't love One Err label style cleanup. The label name is no longer accurate. The cmap is allocated by: err = lynxfb_set_fbinfo(fb_info, fbidx); So ideally there would be a cleanup function which is called something like: lynxfb_unset_fbinfo(fb_info); Then we would only call it if lynxfb_set_fbinfo() succeeds instead of if it succeeds or fails. unset_fb: lynxfb_unset_fbinfo(fb_info); release_fb: framebuffer_release(fb_info); return err; See my blog for more details. staticthinking.wordpress.com/2022/04/28/free-the-last-thing-style/ regards, dan carpenter