summaryrefslogtreecommitdiffstats
path: root/net/ax25
diff options
context:
space:
mode:
authorFrancois Romieu <romieu@fr.zoreil.com>2022-08-02 17:07:42 +0200
committerJakub Kicinski <kuba@kernel.org>2022-08-05 19:00:02 -0700
commitdf1c941468fca014ad092f76672966bb412c2848 (patch)
tree8978c17dde437068157b2114802021ea5079f3aa /net/ax25
parent13c9f4dc102f2856e80b92486c41841e25e23772 (diff)
downloadlinux-df1c941468fca014ad092f76672966bb412c2848.tar.bz2
net: avoid overflow when rose /proc displays timer information.
rose /proc code does not serialize timer accesses. Initial report by Bernard F6BVP Pidoux exhibits overflow amounting to 116 ticks on its HZ=250 system. Full timer access serialization would imho be overkill as rose /proc does not enforce consistency between displayed ROSE_STATE_XYZ and timer values during changes of state. The patch may also fix similar behavior in ax25 /proc, ax25 ioctl and netrom /proc as they all exhibit the same timer serialization policy. This point has not been reported though. The sole remaining use of ax25_display_timer - ax25 rtt valuation - may also perform marginally better but I have not analyzed it too deeply. Cc: Thomas DL9SAU Osterried <thomas@osterried.de> Link: https://lore.kernel.org/all/d5e93cc7-a91f-13d3-49a1-b50c11f0f811@free.fr/ Signed-off-by: Francois Romieu <romieu@fr.zoreil.com> Tested-by: Bernard Pidoux <f6bvp@free.fr> Link: https://lore.kernel.org/r/Yuk9vq7t7VhmnOXu@electric-eye.fr.zoreil.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/ax25')
-rw-r--r--net/ax25/ax25_timer.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/net/ax25/ax25_timer.c b/net/ax25/ax25_timer.c
index 85865ebfdfa2..9f7cb0a7c73f 100644
--- a/net/ax25/ax25_timer.c
+++ b/net/ax25/ax25_timer.c
@@ -108,10 +108,12 @@ int ax25_t1timer_running(ax25_cb *ax25)
unsigned long ax25_display_timer(struct timer_list *timer)
{
+ long delta = timer->expires - jiffies;
+
if (!timer_pending(timer))
return 0;
- return timer->expires - jiffies;
+ return max(0L, delta);
}
EXPORT_SYMBOL(ax25_display_timer);