From d15809f3649e2ee04713a9dba9aa7bd2c208ad82 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Fri, 17 Nov 2017 15:27:13 -0800 Subject: iopoll: avoid -Wint-in-bool-context warning When we pass the result of a multiplication as the timeout or the delay, we can get a warning from gcc-7: drivers/mmc/host/bcm2835.c:596:149: error: '*' in boolean context, suggest '&&' instead [-Werror=int-in-bool-context] drivers/mfd/arizona-core.c:247:195: error: '*' in boolean context, suggest '&&' instead [-Werror=int-in-bool-context] drivers/gpu/drm/sun4i/sun4i_hdmi_i2c.c:49:27: error: '*' in boolean context, suggest '&&' instead [-Werror=int-in-bool-context] The warning is a bit questionable inside of a macro, but this is intentional on the side of the gcc developers. It is also an indication of another problem: we evaluate the timeout and sleep arguments multiple times, which can have undesired side-effects when those are complex expressions. This changes the two iopoll variants to use local variables for storing copies of the timeouts. This adds some more type safety, and avoids both the double-evaluation and the gcc warning. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81484 Link: http://lkml.kernel.org/r/20170726133756.2161367-1-arnd@arndb.de Link: http://lkml.kernel.org/r/20171102114048.1526955-1-arnd@arndb.de Signed-off-by: Arnd Bergmann Reviewed-by: Mark Brown Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/iopoll.h | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) (limited to 'include') diff --git a/include/linux/iopoll.h b/include/linux/iopoll.h index d29e1e21bf3f..b1d861caca16 100644 --- a/include/linux/iopoll.h +++ b/include/linux/iopoll.h @@ -42,18 +42,21 @@ */ #define readx_poll_timeout(op, addr, val, cond, sleep_us, timeout_us) \ ({ \ - ktime_t timeout = ktime_add_us(ktime_get(), timeout_us); \ - might_sleep_if(sleep_us); \ + u64 __timeout_us = (timeout_us); \ + unsigned long __sleep_us = (sleep_us); \ + ktime_t __timeout = ktime_add_us(ktime_get(), __timeout_us); \ + might_sleep_if((__sleep_us) != 0); \ for (;;) { \ (val) = op(addr); \ if (cond) \ break; \ - if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { \ + if (__timeout_us && \ + ktime_compare(ktime_get(), __timeout) > 0) { \ (val) = op(addr); \ break; \ } \ - if (sleep_us) \ - usleep_range((sleep_us >> 2) + 1, sleep_us); \ + if (__sleep_us) \ + usleep_range((__sleep_us >> 2) + 1, __sleep_us); \ } \ (cond) ? 0 : -ETIMEDOUT; \ }) @@ -77,17 +80,20 @@ */ #define readx_poll_timeout_atomic(op, addr, val, cond, delay_us, timeout_us) \ ({ \ - ktime_t timeout = ktime_add_us(ktime_get(), timeout_us); \ + u64 __timeout_us = (timeout_us); \ + unsigned long __delay_us = (delay_us); \ + ktime_t __timeout = ktime_add_us(ktime_get(), __timeout_us); \ for (;;) { \ (val) = op(addr); \ if (cond) \ break; \ - if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { \ + if (__timeout_us && \ + ktime_compare(ktime_get(), __timeout) > 0) { \ (val) = op(addr); \ break; \ } \ - if (delay_us) \ - udelay(delay_us); \ + if (__delay_us) \ + udelay(__delay_us); \ } \ (cond) ? 0 : -ETIMEDOUT; \ }) -- cgit