| Message ID | 1456400265-3068525-1-git-send-email-arnd@arndb.de (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 14a20428e2e02600195a71ad366c0caef97bf3d4 |
| Headers | show |
On Thu, 2016-02-25 at 12:37 +0100, Arnd Bergmann wrote: > The spi_lp8841_rtc_probe() function misses an initialization of the > return code when it fails to get its memory resource, as gcc notices: > > drivers/spi/spi-lp8841-rtc.c: In function 'spi_lp8841_rtc_probe': > drivers/spi/spi-lp8841-rtc.c:239:9: error: 'ret' may be used > uninitialized in this function [-Werror=maybe-uninitialized] > > This changes the code to propagate the error from > devm_ioremap_resource(). > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > Fixes: 7ecbfff6711f ("spi: master driver to enable RTC on ICPDAS LP- > 8841") Tested-by: Sergei Ianovich <ynvich@gmail.com> -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Arnd, On Thu, 2016-02-25 at 12:37 +0100, Arnd Bergmann wrote: > The spi_lp8841_rtc_probe() function misses an initialization of the > return code when it fails to get its memory resource, as gcc notices: > > drivers/spi/spi-lp8841-rtc.c: In function 'spi_lp8841_rtc_probe': > drivers/spi/spi-lp8841-rtc.c:239:9: error: 'ret' may be used > uninitialized in this function [-Werror=maybe-uninitialized] I wasn't getting this warning when I was building the driver. This happened because -Wmaybe-uninitialized is suppressed when CONFIG_CC_OPTIMIZE_FOR_SIZE is selected (Commit e74fc973b6e531fef1fce8b101ffff05ecfb774c "Turn off -Wmaybe- uninitialized when building with -Os"). A recent gcc version like 5.3.1 doesn't seem to produce much false positives. May it make sense to revert that commit? The gcc-5.3.1 log for reference. ---8<--- $ arm-linux-gnueabi-gcc --version arm-linux-gnueabi-gcc (Debian 5.3.1-8) 5.3.1 20160205 $ make -j 4 -s KCFLAGS=-Wmaybe-uninitialized ipc/shm.c: In function 'SyS_shmdt': ipc/shm.c:1344:59: warning: 'file' may be used uninitialized in this function [-Wmaybe-uninitialized] ((vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) && ^ ipc/shm.c:1267:15: note: 'file' was declared here struct file *file; ^ mm/vmscan.c: In function 'shrink_zone': mm/vmscan.c:2418:18: warning: 'lru_pages' may be used uninitialized in this function [-Wmaybe-uninitialized] unsigned long lru_pages; ^ drivers/gpio/gpiolib-of.c: In function 'of_gpiochip_add': drivers/gpio/gpiolib-of.c:221:7: warning: 'dflags' may be used uninitialized in this function [-Wmaybe-uninitialized] if (gpiod_hog(desc, name, lflags, dflags)) ^ drivers/gpio/gpiolib-of.c:211:19: note: 'dflags' was declared here enum gpiod_flags dflags; ^ drivers/gpio/gpiolib-of.c:221:7: warning: 'lflags' may be used uninitialized in this function [-Wmaybe-uninitialized] if (gpiod_hog(desc, name, lflags, dflags)) ^ drivers/gpio/gpiolib-of.c:210:25: note: 'lflags' was declared here enum gpio_lookup_flags lflags; ^ net/core/dev.c: In function 'validate_xmit_skb_list': net/core/dev.c:2984:15: warning: 'tail' may be used uninitialized in this function [-Wmaybe-uninitialized] tail->next = skb; ^ drivers/spi/spi-lp8841-rtc.c: In function 'spi_lp8841_rtc_probe': drivers/spi/spi-lp8841-rtc.c:239:9: warning: 'ret' may be used uninitialized in this function [-Wmaybe-uninitialized] return ret; ^ net/sunrpc/svcauth_unix.c: In function 'unix_gid_parse': net/sunrpc/svcauth_unix.c:510:2: warning: 'gids' may be used uninitialized in this function [-Wmaybe-uninitialized] for (i = 0 ; i < gids ; i++) { ^ In file included from include/linux/sunrpc/svcauth.h:16:0, from include/linux/sunrpc/svc.h:18, from include/linux/sunrpc/svcsock.h:12, from net/sunrpc/svcauth_unix.c:6: include/linux/sunrpc/cache.h:306:9: warning: 'rv' may be used uninitialized in this function [-Wmaybe-uninitialized] return rv - boot.tv_sec; ^ include/linux/sunrpc/cache.h:298:9: note: 'rv' was declared here time_t rv; ^ net/sunrpc/svcauth_unix.c: In function 'ip_map_parse': include/linux/sunrpc/cache.h:306:9: warning: 'rv' may be used uninitialized in this function [-Wmaybe-uninitialized] return rv - boot.tv_sec; ^ include/linux/sunrpc/cache.h:298:9: note: 'rv' was declared here time_t rv; ^ In file included from net/sunrpc/cache.c:34:0: net/sunrpc/cache.c: In function 'write_flush': include/linux/sunrpc/cache.h:306:9: warning: 'rv' may be used uninitialized in this function [-Wmaybe-uninitialized] return rv - boot.tv_sec; ^ include/linux/sunrpc/cache.h:298:9: note: 'rv' was declared here time_t rv; ^ net/sunrpc/auth_gss/svcauth_gss.c: In function 'rsc_parse': net/sunrpc/auth_gss/svcauth_gss.c:456:22: warning: 'id' may be used uninitialized in this function [-Wmaybe-uninitialized] rsci.cred.cr_uid = make_kuid(&init_user_ns, id); ^ In file included from include/linux/sunrpc/svcauth.h:16:0, from include/linux/sunrpc/svc.h:18, from include/linux/sunrpc/auth_gss.h:17, from net/sunrpc/auth_gss/svcauth_gss.c:46: include/linux/sunrpc/cache.h:306:9: warning: 'rv' may be used uninitialized in this function [-Wmaybe-uninitialized] return rv - boot.tv_sec; ^ include/linux/sunrpc/cache.h:298:9: note: 'rv' was declared here time_t rv; ^ net/sunrpc/auth_gss/svcauth_gss.c: In function 'rsi_parse': include/linux/sunrpc/cache.h:306:9: warning: 'rv' may be used uninitialized in this function [-Wmaybe-uninitialized] return rv - boot.tv_sec; ^ include/linux/sunrpc/cache.h:298:9: note: 'rv' was declared here time_t rv; ^ ---8<--- -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Saturday 27 February 2016 22:32:57 Sergei Ianovich wrote: > Hi Arnd, > > On Thu, 2016-02-25 at 12:37 +0100, Arnd Bergmann wrote: > > The spi_lp8841_rtc_probe() function misses an initialization of the > > return code when it fails to get its memory resource, as gcc notices: > > > > drivers/spi/spi-lp8841-rtc.c: In function 'spi_lp8841_rtc_probe': > > drivers/spi/spi-lp8841-rtc.c:239:9: error: 'ret' may be used > > uninitialized in this function [-Werror=maybe-uninitialized] > > I wasn't getting this warning when I was building the driver. This > happened because -Wmaybe-uninitialized is suppressed when > CONFIG_CC_OPTIMIZE_FOR_SIZE is selected > (Commit e74fc973b6e531fef1fce8b101ffff05ecfb774c "Turn off -Wmaybe- > uninitialized when building with -Os"). > > A recent gcc version like 5.3.1 doesn't seem to produce much false > positives. May it make sense to revert that commit? > > The gcc-5.3.1 log for reference. I have spent a lot of time on fixing those warning messages. I still see tons of warnings even with the latest compilers when -Os (all false positives) is used, and I have a branch in which I have fixed all the ones that happen when building with -O2. I recently submitted a patch to turn CONFIG_CC_OPTIMIZE_FOR_SIZE into a choice statement that is not automatically set on an allmodconfig build, which should help here, but my patch has not yet been merged. We have similar problems with a couple of other options that drastically increase the false positive rate for these warnings (GCOV_PROFILE_ALL, PROFILE_ALL_BRANCHES, UBSAN_SANTIZE_ALL, ...), and I think our best strategy for all of these is to make sure they are not enabled in an allmodconfig build or the typical defconfigs, but also to hide the warnings if they are used in a particular config. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/spi/spi-lp8841-rtc.c b/drivers/spi/spi-lp8841-rtc.c index 44bb69c3f1d6..faa577d282c0 100644 --- a/drivers/spi/spi-lp8841-rtc.c +++ b/drivers/spi/spi-lp8841-rtc.c @@ -217,8 +217,9 @@ spi_lp8841_rtc_probe(struct platform_device *pdev) data = spi_master_get_devdata(master); iomem = platform_get_resource(pdev, IORESOURCE_MEM, 0); - data->iomem = devm_ioremap_resource(&pdev->dev, iomem); - if (IS_ERR(data->iomem)) { + data->iomem = devm_ioremap_resource(&pdev->dev, iomem); + ret = PTR_ERR_OR_ZERO(data->iomem); + if (ret) { dev_err(&pdev->dev, "failed to get IO address\n"); goto err_put_master; }
The spi_lp8841_rtc_probe() function misses an initialization of the return code when it fails to get its memory resource, as gcc notices: drivers/spi/spi-lp8841-rtc.c: In function 'spi_lp8841_rtc_probe': drivers/spi/spi-lp8841-rtc.c:239:9: error: 'ret' may be used uninitialized in this function [-Werror=maybe-uninitialized] This changes the code to propagate the error from devm_ioremap_resource(). Signed-off-by: Arnd Bergmann <arnd@arndb.de> Fixes: 7ecbfff6711f ("spi: master driver to enable RTC on ICPDAS LP-8841") --- drivers/spi/spi-lp8841-rtc.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)