From: Coly Li Date: Fri, 10 Aug 2018 15:45:50 +0000 (+0800) Subject: bcache: fix error setting writeback_rate through sysfs interface X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=46451874c7c9afaa4e014aea0f0970f886444e0d;p=openwrt%2Fstaging%2Fblogic.git bcache: fix error setting writeback_rate through sysfs interface Commit ea8c5356d390 ("bcache: set max writeback rate when I/O request is idle") changes struct bch_ratelimit member rate from uint32_t to atomic_long_t and uses atomic_long_set() in drivers/md/bcache/sysfs.c to set new writeback rate, after the input is converted from memory buf to long int by sysfs_strtoul_clamp(). The above change has a problem because there is an implicit return inside sysfs_strtoul_clamp() so the following atomic_long_set() won't be called. This error is detected by 0day system with following snipped smatch warnings: drivers/md/bcache/sysfs.c:271 __cached_dev_store() error: uninitialized symbol 'v'. 270 sysfs_strtoul_clamp(writeback_rate, v, 1, INT_MAX); ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ @271 atomic_long_set(&dc->writeback_rate.rate, v); This patch fixes the above error by using strtoul_safe_clamp() to convert the input buffer into a long int type result. Fixes: ea8c5356d390 ("bcache: set max writeback rate when I/O request is idle") Cc: Kai Krakow Cc: Stefan Priebe Signed-off-by: Coly Li Signed-off-by: Jens Axboe --- diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c index 22f8565d2bf1..81d3520b0702 100644 --- a/drivers/md/bcache/sysfs.c +++ b/drivers/md/bcache/sysfs.c @@ -265,10 +265,17 @@ STORE(__cached_dev) sysfs_strtoul_clamp(writeback_percent, dc->writeback_percent, 0, 40); if (attr == &sysfs_writeback_rate) { - int v; + ssize_t ret; + long int v = atomic_long_read(&dc->writeback_rate.rate); + + ret = strtoul_safe_clamp(buf, v, 1, INT_MAX); - sysfs_strtoul_clamp(writeback_rate, v, 1, INT_MAX); - atomic_long_set(&dc->writeback_rate.rate, v); + if (!ret) { + atomic_long_set(&dc->writeback_rate.rate, v); + ret = size; + } + + return ret; } sysfs_strtoul_clamp(writeback_rate_update_seconds,