On 10/30/2018 3:22 PM, kbuild test robot wrote:
Hi Jae,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on wsa/i2c/for-next]
[also build test WARNING on v4.19 next-20181030]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Jae-Hyun-Yoo/dt-bindings-i2c-Add-bus-timeout-ms-and-retries-properties-as-common-optional/20181031-051152
base: https://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git i2c/for-next
config: xtensa-allyesconfig (attached as .config)
compiler: xtensa-linux-gcc (GCC) 8.1.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
GCC_VERSION=8.1.0 make.cross ARCH=xtensa
Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings
All warnings (new ones prefixed by >>):
In file included from include/linux/ktime.h:25,
from include/linux/rcutiny.h:28,
from include/linux/rcupdate.h:209,
from include/linux/srcu.h:33,
from include/linux/notifier.h:16,
from include/linux/clk.h:17,
from drivers/i2c/busses/i2c-aspeed.c:13:
drivers/i2c/busses/i2c-aspeed.c: In function 'aspeed_i2c_master_xfer':
include/linux/jiffies.h:108:15: warning: 'timeout' may be used uninitialized in this function [-Wmaybe-uninitialized]
((long)((b) - (a)) < 0))
^
drivers/i2c/busses/i2c-aspeed.c:607:16: note: 'timeout' was declared here
unsigned long timeout;
^~~~~~~
--
In file included from include/linux/ktime.h:25,
from include/linux/rcutiny.h:28,
from include/linux/rcupdate.h:209,
from include/linux/srcu.h:33,
from include/linux/notifier.h:16,
from include/linux/clk.h:17,
from drivers/i2c//busses/i2c-aspeed.c:13:
drivers/i2c//busses/i2c-aspeed.c: In function 'aspeed_i2c_master_xfer':
include/linux/jiffies.h:108:15: warning: 'timeout' may be used uninitialized in this function [-Wmaybe-uninitialized]
((long)((b) - (a)) < 0))
^
drivers/i2c//busses/i2c-aspeed.c:607:16: note: 'timeout' was declared here
unsigned long timeout;
^~~~~~~
vim +/timeout +108 include/linux/jiffies.h
^1da177e Linus Torvalds 2005-04-16 91
^1da177e Linus Torvalds 2005-04-16 92 /*
^1da177e Linus Torvalds 2005-04-16 93 * These inlines deal with timer wrapping correctly. You are
^1da177e Linus Torvalds 2005-04-16 94 * strongly encouraged to use them
^1da177e Linus Torvalds 2005-04-16 95 * 1. Because people otherwise forget
^1da177e Linus Torvalds 2005-04-16 96 * 2. Because if the timer wrap changes in future you won't have to
^1da177e Linus Torvalds 2005-04-16 97 * alter your driver code.
^1da177e Linus Torvalds 2005-04-16 98 *
^1da177e Linus Torvalds 2005-04-16 99 * time_after(a,b) returns true if the time a is after time b.
^1da177e Linus Torvalds 2005-04-16 100 *
^1da177e Linus Torvalds 2005-04-16 101 * Do this with "<0" and ">=0" to only test the sign of the result. A
^1da177e Linus Torvalds 2005-04-16 102 * good compiler would generate better code (and a really good compiler
^1da177e Linus Torvalds 2005-04-16 103 * wouldn't care). Gcc is currently neither.
^1da177e Linus Torvalds 2005-04-16 104 */
^1da177e Linus Torvalds 2005-04-16 105 #define time_after(a,b) \
^1da177e Linus Torvalds 2005-04-16 106 (typecheck(unsigned long, a) && \
^1da177e Linus Torvalds 2005-04-16 107 typecheck(unsigned long, b) && \
5a581b36 Paul E. McKenney 2013-07-27 @108 ((long)((b) - (a)) < 0))
^1da177e Linus Torvalds 2005-04-16 109 #define time_before(a,b) time_after(b,a)
^1da177e Linus Torvalds 2005-04-16 110
:::::: The code at line 108 was first introduced by commit
:::::: 5a581b367b5df0531265311fc681c2abd377e5e6 jiffies: Avoid undefined behavior from signed overflow
:::::: TO: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
:::::: CC: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
This is a false warning.
The 'timeout' local variable will be initialized properly if it's gonna
be used when the multi-master property is set.
-Jae
