From a1d75dad3a2c689e70a1c4e0214cca9de741d0aa Mon Sep 17 00:00:00 2001 From: Zhi Jin Date: Thu, 6 Sep 2018 15:22:10 +0800 Subject: stm class: Fix an endless loop in channel allocation There is a bug in the channel allocation logic that leads to an endless loop when looking for a contiguous range of channels in a range with a mixture of free and occupied channels. For example, opening three consequtive channels, closing the first two and requesting 4 channels in a row will trigger this soft lockup. The bug is that the search loop forgets to skip over the range once it detects that one channel in that range is occupied. Restore the original intent to the logic by fixing the omission. Signed-off-by: Zhi Jin Signed-off-by: Alexander Shishkin Fixes: 7bd1d4093c2f ("stm class: Introduce an abstraction for System Trace Module devices") CC: stable@vger.kernel.org # v4.4+ --- drivers/hwtracing/stm/core.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers/hwtracing/stm') diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c index 93ce3aa740a9..c80b064224f6 100644 --- a/drivers/hwtracing/stm/core.c +++ b/drivers/hwtracing/stm/core.c @@ -244,6 +244,9 @@ static int find_free_channels(unsigned long *bitmap, unsigned int start, ; if (i == width) return pos; + + /* step over [pos..pos+i) to continue search */ + pos += i; } return -1; -- cgit