On Mon, 23 Jul 2018, Randy Dunlap wrote: > On 07/20/2018 12:20 AM, Andreas Schwab wrote: > > On Jul 19 2018, Randy Dunlap <rdun...@infradead.org> wrote: > > > >> block/partitions/ldm.o: In function `ldm_partition': > >> ldm.c:(.text+0x1900): undefined reference to `strcmp' > >> ldm.c:(.text+0x1964): undefined reference to `strcmp' > >> drivers/rtc/rtc-proc.o: In function `is_rtc_hctosys': > >> rtc-proc.c:(.text+0x290): undefined reference to `strcmp' > >> drivers/watchdog/watchdog_pretimeout.o: In function > >> `watchdog_register_governor': > >> (.text+0x142): undefined reference to `strcmp' > > > > GCC has optimized strncmp to strcmp, but at a stage where macros are no > > longer available. I think the right fix is to use strcmp directly, > > since strncmp doesn't make sense here. > > Hi Andreas, > > I don't see that all of these string compare fields are null-terminated. >
Some of the strncmp calls in ldm.c are null-terminated, some are not. That would imply that the compiler will emit both strcmp and strncmp calls. A strncmp call isn't a problem, because m68k doesn't define __HAVE_ARCH_STRNCMP and so the one from lib/string.c gets built. > How does one convert strncmp() users to strcmp()? > > thanks, > The untested patch below may work. It seems that it may be relevant to both arc and m68k: $ diff -u <(egrep -rlw __HAVE_ARCH_STRCMP *) <(egrep -rlw __HAVE_ARCH_STRNCMP *) --- /dev/fd/63 2018-07-24 14:22:56.180014584 +1000 +++ /dev/fd/62 2018-07-24 14:22:56.180014584 +1000 @@ -1,11 +1,12 @@ arch/mips/include/asm/string.h arch/x86/lib/string_32.c arch/x86/include/asm/string_32.h -arch/m68k/include/asm/string.h arch/xtensa/include/asm/string.h arch/sh/include/asm/string_32.h +arch/powerpc/include/asm/string.h arch/s390/include/asm/string.h arch/arm64/include/asm/string.h -arch/arc/include/asm/string.h +arch/sparc/include/asm/string.h +drivers/firmware/efi/libstub/string.c include/linux/string.h lib/string.c How can all those __HAVE_ARCH_FOO feature macros work properly if the compiler makes assumptions about libc availability? Isn't that assumption invalidated by -ffreestanding? Surely the strcmp optimization is only valid when there is a __builtin_strcmp? -- diff --git a/block/partitions/ldm.c b/block/partitions/ldm.c index 0417937dfe99..4b9927344593 100644 --- a/block/partitions/ldm.c +++ b/block/partitions/ldm.c @@ -150,8 +150,7 @@ static bool ldm_parse_tocblock (const u8 *data, struct tocblock *toc) toc->bitmap1_start = get_unaligned_be64(data + 0x2E); toc->bitmap1_size = get_unaligned_be64(data + 0x36); - if (strncmp (toc->bitmap1_name, TOC_BITMAP1, - sizeof (toc->bitmap1_name)) != 0) { + if (strcmp(toc->bitmap1_name, TOC_BITMAP1) != 0) { ldm_crit ("TOCBLOCK's first bitmap is '%s', should be '%s'.", TOC_BITMAP1, toc->bitmap1_name); return false; @@ -160,8 +159,7 @@ static bool ldm_parse_tocblock (const u8 *data, struct tocblock *toc) toc->bitmap2_name[sizeof (toc->bitmap2_name) - 1] = 0; toc->bitmap2_start = get_unaligned_be64(data + 0x50); toc->bitmap2_size = get_unaligned_be64(data + 0x58); - if (strncmp (toc->bitmap2_name, TOC_BITMAP2, - sizeof (toc->bitmap2_name)) != 0) { + if (strcmp(toc->bitmap2_name, TOC_BITMAP2) != 0) { ldm_crit ("TOCBLOCK's second bitmap is '%s', should be '%s'.", TOC_BITMAP2, toc->bitmap2_name); return false; diff --git a/drivers/rtc/rtc-proc.c b/drivers/rtc/rtc-proc.c index a9dd9218fae2..5f9a5a720b4d 100644 --- a/drivers/rtc/rtc-proc.c +++ b/drivers/rtc/rtc-proc.c @@ -30,7 +30,7 @@ static bool is_rtc_hctosys(struct rtc_device *rtc) if (size > NAME_SIZE) return false; - return !strncmp(name, CONFIG_RTC_HCTOSYS_DEVICE, NAME_SIZE); + return !strcmp(name, CONFIG_RTC_HCTOSYS_DEVICE); } #else static bool is_rtc_hctosys(struct rtc_device *rtc) diff --git a/drivers/watchdog/watchdog_pretimeout.c b/drivers/watchdog/watchdog_pretimeout.c index 9db07bfb4334..d4797452b011 100644 --- a/drivers/watchdog/watchdog_pretimeout.c +++ b/drivers/watchdog/watchdog_pretimeout.c @@ -136,8 +136,7 @@ int watchdog_register_governor(struct watchdog_governor *gov) priv->gov = gov; list_add(&priv->entry, &governor_list); - if (!strncmp(gov->name, WATCHDOG_PRETIMEOUT_DEFAULT_GOV, - WATCHDOG_GOV_NAME_MAXLEN)) { + if (!strcmp(gov->name, WATCHDOG_PRETIMEOUT_DEFAULT_GOV)) { spin_lock_irq(&pretimeout_lock); default_gov = gov;