From: "Måns Rullgård" <mans@mansr.com> To: Arnd Bergmann <arnd@arndb.de> Cc: "David S. Miller" <davem@davemloft.net>, linux-arm-kernel@lists.infradead.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 8/9] net: nb8800: avoid uninitialized variable warning Date: Wed, 27 Jan 2016 14:13:16 +0000 [thread overview] Message-ID: <yw1xsi1jjekj.fsf@unicorn.mansr.com> (raw) In-Reply-To: <1453903507-3427225-9-git-send-email-arnd@arndb.de> (Arnd Bergmann's message of "Wed, 27 Jan 2016 15:04:58 +0100") Arnd Bergmann <arnd@arndb.de> writes: > The nb8800_poll() function initializes the 'next' variable in the > loop looking for new input data. We know this will be called at > least once because 'budget' is a guaranteed to be a positive number > when we enter the function, but the compiler doesn't know that > and warns when the variable is used later: > > drivers/net/ethernet/aurora/nb8800.c: In function 'nb8800_poll': > drivers/net/ethernet/aurora/nb8800.c:350:21: warning: 'next' may be used uninitialized in this function [-Wmaybe-uninitialized] Which gcc version is this? 4.9 doesn't warn here, presumably because it's clever enough to notice that the offending use of 'next' is under a condition that can only be true if the first one was. Of course fixing the code so older compilers don't warn is a good idea. > Changing the 'while() {}' loop to 'do {} while()' makes it obvious > to the compiler what is going on so it no longer warns. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Mans Rullgard <mans@mansr.com> > --- > drivers/net/ethernet/aurora/nb8800.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/ethernet/aurora/nb8800.c b/drivers/net/ethernet/aurora/nb8800.c > index ecc4a334c507..f71ab2647a3b 100644 > --- a/drivers/net/ethernet/aurora/nb8800.c > +++ b/drivers/net/ethernet/aurora/nb8800.c > @@ -302,7 +302,7 @@ static int nb8800_poll(struct napi_struct *napi, int budget) > nb8800_tx_done(dev); > > again: > - while (work < budget) { > + do { > struct nb8800_rx_buf *rxb; > unsigned int len; > > @@ -330,7 +330,7 @@ again: > rxd->report = 0; > last = next; > work++; > - } > + } while (work < budget); > > if (work) { > priv->rx_descs[last].desc.config |= DESC_EOC; > -- > 2.7.0 > -- Måns Rullgård
WARNING: multiple messages have this Message-ID (diff)
From: mans@mansr.com (Måns Rullgård) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH 8/9] net: nb8800: avoid uninitialized variable warning Date: Wed, 27 Jan 2016 14:13:16 +0000 [thread overview] Message-ID: <yw1xsi1jjekj.fsf@unicorn.mansr.com> (raw) In-Reply-To: <1453903507-3427225-9-git-send-email-arnd@arndb.de> (Arnd Bergmann's message of "Wed, 27 Jan 2016 15:04:58 +0100") Arnd Bergmann <arnd@arndb.de> writes: > The nb8800_poll() function initializes the 'next' variable in the > loop looking for new input data. We know this will be called at > least once because 'budget' is a guaranteed to be a positive number > when we enter the function, but the compiler doesn't know that > and warns when the variable is used later: > > drivers/net/ethernet/aurora/nb8800.c: In function 'nb8800_poll': > drivers/net/ethernet/aurora/nb8800.c:350:21: warning: 'next' may be used uninitialized in this function [-Wmaybe-uninitialized] Which gcc version is this? 4.9 doesn't warn here, presumably because it's clever enough to notice that the offending use of 'next' is under a condition that can only be true if the first one was. Of course fixing the code so older compilers don't warn is a good idea. > Changing the 'while() {}' loop to 'do {} while()' makes it obvious > to the compiler what is going on so it no longer warns. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Mans Rullgard <mans@mansr.com> > --- > drivers/net/ethernet/aurora/nb8800.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/ethernet/aurora/nb8800.c b/drivers/net/ethernet/aurora/nb8800.c > index ecc4a334c507..f71ab2647a3b 100644 > --- a/drivers/net/ethernet/aurora/nb8800.c > +++ b/drivers/net/ethernet/aurora/nb8800.c > @@ -302,7 +302,7 @@ static int nb8800_poll(struct napi_struct *napi, int budget) > nb8800_tx_done(dev); > > again: > - while (work < budget) { > + do { > struct nb8800_rx_buf *rxb; > unsigned int len; > > @@ -330,7 +330,7 @@ again: > rxd->report = 0; > last = next; > work++; > - } > + } while (work < budget); > > if (work) { > priv->rx_descs[last].desc.config |= DESC_EOC; > -- > 2.7.0 > -- M?ns Rullg?rd
next prev parent reply other threads:[~2016-01-27 14:13 UTC|newest] Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-01-27 14:04 [PATCH 0/9] network driver fixes Arnd Bergmann 2016-01-27 14:04 ` Arnd Bergmann 2016-01-27 14:04 ` [PATCH 1/9] net: davinci_cpdma: use dma_addr_t for DMA address Arnd Bergmann 2016-01-27 14:04 ` Arnd Bergmann 2016-01-27 14:04 ` [PATCH 2/9] net: hp100: remove unnecessary #ifdefs Arnd Bergmann 2016-01-27 14:04 ` Arnd Bergmann 2016-01-27 14:04 ` [PATCH 3/9] net: bgmac: clarify CONFIG_BCMA dependency Arnd Bergmann 2016-01-27 14:04 ` Arnd Bergmann 2016-01-27 16:11 ` Paul Gortmaker 2016-01-27 16:11 ` Paul Gortmaker 2016-01-27 16:11 ` Paul Gortmaker 2016-01-28 8:49 ` Arnd Bergmann 2016-01-28 8:49 ` Arnd Bergmann 2016-01-27 14:04 ` [PATCH 4/9] net: moxart: use correct accessors for DMA memory Arnd Bergmann 2016-01-27 14:04 ` Arnd Bergmann 2016-01-28 12:36 ` David Laight 2016-01-28 12:36 ` David Laight 2016-01-28 16:53 ` Arnd Bergmann 2016-01-28 16:53 ` Arnd Bergmann 2016-01-28 16:58 ` Arnd Bergmann 2016-01-28 16:58 ` Arnd Bergmann 2016-01-27 14:04 ` [PATCH 5/9] net: fddi/defxx: avoid warning about uninitialized variable use Arnd Bergmann 2016-01-27 14:04 ` Arnd Bergmann 2016-01-27 15:15 ` Maciej W. Rozycki 2016-01-27 15:15 ` Maciej W. Rozycki 2016-01-27 14:04 ` [PATCH 6/9] net: vxge: avoid unused function warnings Arnd Bergmann 2016-01-27 14:04 ` Arnd Bergmann 2016-01-27 14:04 ` [PATCH 7/9] net: macb: avoid uninitialized variables Arnd Bergmann 2016-01-27 14:04 ` Arnd Bergmann 2016-01-27 15:51 ` Nicolas Ferre 2016-01-27 15:51 ` Nicolas Ferre 2016-01-27 16:04 ` Nicolas Ferre 2016-01-27 16:04 ` Nicolas Ferre 2016-01-28 16:32 ` Arnd Bergmann 2016-01-28 16:32 ` Arnd Bergmann 2016-01-28 13:27 ` Sergei Shtylyov 2016-01-28 13:27 ` Sergei Shtylyov 2016-01-27 14:04 ` [PATCH 8/9] net: nb8800: avoid uninitialized variable warning Arnd Bergmann 2016-01-27 14:04 ` Arnd Bergmann 2016-01-27 14:13 ` Måns Rullgård [this message] 2016-01-27 14:13 ` Måns Rullgård 2016-01-27 15:21 ` Arnd Bergmann 2016-01-27 15:21 ` Arnd Bergmann 2016-01-27 14:04 ` [PATCH 9/9] net: tg3: " Arnd Bergmann 2016-01-27 14:04 ` Arnd Bergmann 2016-01-29 0:14 ` [PATCH 0/9] network driver fixes David Miller 2016-01-29 0:14 ` David Miller 2016-01-29 12:56 ` Arnd Bergmann 2016-01-29 12:56 ` Arnd Bergmann
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