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Date: Mon, 1 Aug 2022 17:44:33 +0200 From: Francois Romieu <romieu@...zoreil.com> To: Thomas Osterried <thomas@...erried.de> Cc: Bernard f6bvp <f6bvp@...e.fr>, Eric Dumazet <edumazet@...gle.com>, linux-hams@...r.kernel.org, Thomas Osterried DL9SAU <thomas@...erg.in-berlin.de>, netdev@...r.kernel.org Subject: Re: rose timer t error displayed in /proc/net/rose Thomas Osterried <thomas@...erried.de> : [...] > 1. why do you check for pending timer anymore? s/do/don't/ ? I don't check for pending timer because: - the check is racy - jiffies_delta_to_clock_t maxes negative delta to zero > 2. I'm not really sure what value jiffies_delta_to_clock_t() returns. jiffies / HZ? > jiffies_delta_to_clock_t() returns clock_t. I completely messed this part :o/ clock_t relates to USER_HZ like jiffies does to HZ. [don't break the ax25] Sure, we are in violent agreement here. [...] > 1. I expect rose->timer to be restarted soon. If it does not happen, is there a bug? The relevant rose state in Bernard's sample was ROSE_STATE_2. net/rose/rose_timer.c::rose_timer_expiry would had called rose_disconnect(sk, ETIMEDOUT, -1, -1) so there should not be any timer restart (afaiu, etc.). [...] > => Negative may be handled due to Francois' patch now correctly. > delta as signed long may be negative. max(0L, -nnnn) sould result to 0L. > This would result to 0. Perhaps proven by Francois, because he used this function and achieved a correct display of that idle value. Francois, am I correct, is "0" really displayed? I must confess that I was not terribly professional this morning past 2AM. The attached snippet illustrates the behavior wrt negative values (make; insmod foo.ko ; sleep 1; rmmod foo.ko; dmesg | tail -n 2). It also illustrates that I got the unit wrong. This should be better: diff --git a/net/ax25/ax25_timer.c b/net/ax25/ax25_timer.c index 85865ebfdfa2..3c94e5a2d098 100644 --- a/net/ax25/ax25_timer.c +++ b/net/ax25/ax25_timer.c @@ -108,10 +108,9 @@ int ax25_t1timer_running(ax25_cb *ax25) unsigned long ax25_display_timer(struct timer_list *timer) { - if (!timer_pending(timer)) - return 0; + long delta = timer->expires - jiffies; - return timer->expires - jiffies; + return max(0L, delta); } EXPORT_SYMBOL(ax25_display_timer); View attachment "Makefile" of type "text/plain" (129 bytes) View attachment "foo.c" of type "text/plain" (513 bytes)
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