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[95.249.145.232]) by smtp.gmail.com with ESMTPSA id gq12-20020a170906e24c00b006e067c93e1bsm1929807ejb.39.2022.04.02.03.13.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 02 Apr 2022 03:13:23 -0700 (PDT) From: "Fabio M. De Francesco" To: Ira Weiny , Greg Kroah-Hartman Cc: Larry Finger , Phillip Potter , linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org, outreachy@lists.linux.dev Subject: Re: [PATCH] staging: r8188eu: Remove goto to no-op exit label Date: Sat, 02 Apr 2022 12:13:20 +0200 Message-ID: <1724388.VLH7GnMWUR@leap> In-Reply-To: References: <20220401183513.26222-1-fmdefrancesco@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On venerd? 1 aprile 2022 22:41:40 CEST Ira Weiny wrote: > On Fri, Apr 01, 2022 at 08:35:13PM +0200, Fabio M. De Francesco wrote: > > In function rtw_free_netdev() there are two "goto" jumps to a no-op exit > > label called "RETURN". Remove the label and return in line. > > Thanks for the patch! However, A good commit message lists the why and what of > a change. I don't see a why for this commit? Yes I forgot the "why" :( I'll rework the commit message for v2. > > FWIW (For what it's worth) I know of a couple of good reasons for this change > but you should get in the habit of putting that in the commit message. Even > for obvious things like this. > > Anyway, I think this patch can stand on it's own with an updated commit > message. However, see below... > > > > > Signed-off-by: Fabio M. De Francesco > > --- > > drivers/staging/r8188eu/os_dep/osdep_service.c | 7 ++----- > > 1 file changed, 2 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/staging/r8188eu/os_dep/osdep_service.c b/drivers/staging/r8188eu/os_dep/osdep_service.c > > index 7a6fcc96081a..d680bfba7f5d 100644 > > --- a/drivers/staging/r8188eu/os_dep/osdep_service.c > > +++ b/drivers/staging/r8188eu/os_dep/osdep_service.c > > @@ -117,18 +117,15 @@ void rtw_free_netdev(struct net_device *netdev) > > struct rtw_netdev_priv_indicator *pnpi; > > > > if (!netdev) > > - goto RETURN; > > + return; Actually this function doesn't need to test for a valid "netdev". There are only two callers of this function (they are in os_dep/usb_intf.c) and they already test the pointer soon before calling rtw_free_netdev(). Therefore, I'll remove the test for a valid "netdev" and (obviously) the code has no more need to return at that point in function. > > > > pnpi = netdev_priv(netdev); > > > > if (!pnpi->priv) > > - goto RETURN; > > + return; I cannot see how pnpi->priv might ever be NULL. Pavel Skripkin made me notice that "in rtw_alloc_etherdev() (I can confirm this information because now I've just read the code), if pnpi->priv allocation fails, then netdev will be just freed.". If "netdev" is already free, this function is never called. Therefore, I'll remove this test too. > This does not look right. If netdev is not NULL why does this function skip > free_netdev()? After the two removals I've talked about above, the code will always call vfree(pnpi->priv) and then free_netdev(netdev). Therefore, the code won't anymore skip free_netdev() and the bug is avoided. > > Fabio could you follow up with Larry and/or Phillip and see why the code does > this? To me it looks like a potential bug. > > Thanks! > Ira > > > > > vfree(pnpi->priv); > > free_netdev(netdev); > > - > > -RETURN: > > - return; > > } > > > > int rtw_change_ifname(struct adapter *padapter, const char *ifname) > > -- > > 2.34.1 > > > This is how I think to rework rtw_free_netdev(): void rtw_free_netdev(struct net_device *netdev) { struct rtw_netdev_priv_indicator *pnpi = netdev_priv(netdev); vfree(pnpi->priv); free_netdev(netdev); } Am I missing something? @Greg: please discard this patch; I'll send another that has the purpose to rework rtw_free_netdev() as I showed above for the purpose to avoid redundant tests and avoid the potential skipping of free_netdev() (as Ira has correctly noted, currently we have a bug). Thanks, Fabio