Messages in this thread | | | Subject | Re: [PATCH] spi: lp-8841: return correct error code from probe | From | Sergei Ianovich <> | Date | Sat, 27 Feb 2016 22:32:57 +0300 |
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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<---
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