Hi John, [FYI, it's a private test report for your RFC patch.] [auto build test WARNING on tty/tty-testing] [also build test WARNING on linus/master v5.9-rc1 next-20200819] [cannot apply to tip/locking/core linux/master wq/for-next pmladek/for-next] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/0day-ci/linux/commits/John-Ogness/printk-new-log_cont-... base: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git tty-testing config: x86_64-randconfig-a013-20200818 (attached as .config) compiler: gcc-9 (Debian 9.3.0-15) 9.3.0 reproduce (this is a W=1 build): # save the attached .config to linux build tree make W=1 ARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): kernel/printk/printk.c: In function 'pr_cont_begin': 3497 | text_len = vprintk(fmt, args); | ^~~~~~~~ kernel/printk/printk.c:3505:2: warning: function 'pr_cont_begin' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format] 3505 | c->text_len = vscnprintf(text, CONT_LINE_MAX, fmt, args); | ^ kernel/printk/printk.c: In function 'pr_cont_append': 3561 | text_len = vprintk(fmt, args); | ^~~~~~~~ kernel/printk/printk.c:3571:2: warning: function 'pr_cont_append' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format] 3571 | text_len = vsnprintf(text + c->text_len, CONT_LINE_MAX - c->text_len, fmt, args); | ^~~~~~~~ kernel/printk/printk.c:3585:3: warning: function 'pr_cont_append' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format] 3585 | c->text_len = vscnprintf(text, CONT_LINE_MAX, fmt, args_copy); | ^ # https://github.com/0day-ci/linux/commit/2b9bfd8702672aa1b375a495f3286a277... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review John-Ogness/printk-new-log_cont-implementation/20200820-072853 git checkout 2b9bfd8702672aa1b375a495f3286a277ebf7736 vim +3497 kernel/printk/printk.c 3483 3484 /* alloc buffer, get loglevel, setup initial text */ 3485 int pr_cont_begin(pr_cont_t *c, const char *fmt, ...) 3486 { 3487 int kern_level; 3488 va_list args; 3489 char *text; 3490 3491 c->index = get_cont_buf(); 3492 if (c->index == CONT_BUF_COUNT) { 3493 /* Fallback to printk parts individually. */ 3494 int text_len; 3495 3496 va_start(args, fmt); 3498 va_end(args); 3499 return text_len; 3500 } 3501 3502 text = &cont_buf[c->index][0]; 3503 3504 va_start(args, fmt); 3505 c->text_len = vscnprintf(text, CONT_LINE_MAX, fmt, args); 3506 va_end(args); 3507 3508 c->loglevel = default_message_loglevel; 3509 while (c->text_len > 1 && 3510 (kern_level = printk_get_level(text)) != 0) { 3511 switch (kern_level) { 3512 case '0' ... '7': 3513 c->loglevel = kern_level - '0'; 3514 break; 3515 } 3516 3517 c->text_len -= 2; 3518 memmove(text, text + 2, c->text_len); 3519 } 3520 3521 return c->text_len; 3522 } 3523 3524 /* printk existing buffer, reset buffer */ 3525 void pr_cont_flush(pr_cont_t *c) 3526 { 3527 char *text; 3528 3529 if (c->index == CONT_BUF_COUNT || !c->text_len) 3530 return; 3531 3532 text = &cont_buf[c->index][0]; 3533 3534 printk("%c%c%s\n", KERN_SOH_ASCII, c->loglevel + '0', text); 3535 3536 c->text_len = 0; 3537 } 3538 3539 /* printk existing buffer, free buffer */ 3540 void pr_cont_end(pr_cont_t *c) 3541 { 3542 if (c->index == CONT_BUF_COUNT) 3543 return; 3544 3545 pr_cont_flush(c); 3546 put_cont_buf(c->index); 3547 c->index = CONT_BUF_COUNT; 3548 } 3549 3550 /* append to buffer */ 3551 int pr_cont_append(pr_cont_t *c, const char *fmt, ...) 3552 { 3553 va_list args_copy; 3554 va_list args; 3555 int text_len; 3556 char *text; 3557 3558 if (c->index == CONT_BUF_COUNT) { 3559 /* Fallback to printk parts individually. */ 3560 va_start(args, fmt); --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org