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| author | Francois Romieu <romieu@fr.zoreil.com> | 2022-08-02 17:07:42 +0200 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2022-08-05 19:00:02 -0700 |
| commit | df1c941468fca014ad092f76672966bb412c2848 (patch) | |
| tree | 8978c17dde437068157b2114802021ea5079f3aa /net/ax25 | |
| parent | 13c9f4dc102f2856e80b92486c41841e25e23772 (diff) | |
| download | linux-stable-df1c941468fca014ad092f76672966bb412c2848.tar.gz linux-stable-df1c941468fca014ad092f76672966bb412c2848.tar.bz2 linux-stable-df1c941468fca014ad092f76672966bb412c2848.zip | |
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.c | 4 |
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); |