Re: [PATCH 2.4.22-pre1][NET] timer cleanups
From: Vinay K Nallamothu <hidden>
Date: 2003-09-01 13:59:58
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Hi Dave, On Sun, 2003-08-31 at 09:03, David S. Miller wrote:
On Sat, 30 Aug 2003 21:11:37 +0530 Vinay K Nallamothu [off-list ref] wrote:quoted
This patch does the following timer code cleanup: 1. Change del_timer/add_timer to mod_timer 2. Use static timer initialisation wherever applicableI'm not accepting this. In particular, the ip6_flowlabel.c change is a bad idea because the code remains racey.
Someone submitted a similar move to mod_timer() for ip6_flowlabel
That too was submitted by me. Unfortunately I never got to see your mail. No excuses though.
Just blindly doing these kinds of conversions to mod_timer() is foolhardy. You need to apply some brains to it to make sure you really are getting rid of whatever potential races exist in the code.
You are correct. While I tried to make sure that new bugs are not introduced, I haven't paid attention to the existing ones.
And in the ip6_flowlabel.c case things are as buggy as they were before.
Please find the updated patch below and let me know if it's ok. Thanks Vinay ip6_flowlabel.c: 1. Use static timer initializer 2. Use timer macros to handle jiffie wrap in comparisions 3. Convert del_timer/add_timer to mod_timer ip6_flowlabel.c | 30 ++++++++++++++++-------------- 1 files changed, 16 insertions(+), 14 deletions(-) diff -urN linux-2.4.22/net/ipv6/ip6_flowlabel.c linux-2.4.22-nvk/net/ipv6/ip6_flowlabel.c
--- linux-2.4.22/net/ipv6/ip6_flowlabel.c 2003-06-14 10:03:12.000000000 +0530
+++ linux-2.4.22-nvk/net/ipv6/ip6_flowlabel.c 2003-09-01 16:47:03.000000000 +0530@@ -48,7 +48,8 @@ static atomic_t fl_size = ATOMIC_INIT(0); static struct ip6_flowlabel *fl_ht[FL_HASH_MASK+1]; -static struct timer_list ip6_fl_gc_timer; +static void ip6_fl_gc(unsigned long dummy); +static struct timer_list ip6_fl_gc_timer = TIMER_INITIALIZER(ip6_fl_gc, 0, 0); /* FL hash table lock: it protects only of GC */
@@ -92,10 +93,12 @@ static void fl_release(struct ip6_flowlabel *fl) { + write_lock_bh(&ip6_fl_lock); + fl->lastuse = jiffies; if (atomic_dec_and_test(&fl->users)) { unsigned long ttd = fl->lastuse + fl->linger; - if ((long)(ttd - fl->expires) > 0) + if (time_after(ttd, fl->expires)) fl->expires = ttd; ttd = fl->expires; if (fl->opt && fl->share == IPV6_FL_S_EXCL) {
@@ -103,11 +106,12 @@ fl->opt = NULL; kfree(opt); } - if (!del_timer(&ip6_fl_gc_timer) || - (long)(ip6_fl_gc_timer.expires - ttd) > 0) - ip6_fl_gc_timer.expires = ttd; - add_timer(&ip6_fl_gc_timer); + if (!timer_pending(&ip6_fl_gc_timer) || + time_after(ip6_fl_gc_timer.expires, ttd)) + mod_timer(&ip6_fl_gc_timer, ttd); } + + write_unlock_bh(&ip6_fl_lock); } static void ip6_fl_gc(unsigned long dummy)
@@ -124,16 +128,16 @@ while ((fl=*flp) != NULL) { if (atomic_read(&fl->users) == 0) { unsigned long ttd = fl->lastuse + fl->linger; - if ((long)(ttd - fl->expires) > 0) + if (time_after(ttd, fl->expires)) fl->expires = ttd; ttd = fl->expires; - if ((long)(now - ttd) >= 0) { + if (time_after_eq(now, ttd)) { *flp = fl->next; fl_free(fl); atomic_dec(&fl_size); continue; } - if (!sched || (long)(ttd - sched) < 0) + if (!sched || time_before(ttd, sched)) sched = ttd; } flp = &fl->next;
@@ -262,11 +266,11 @@ if (!expires) return -EPERM; fl->lastuse = jiffies; - if (fl->linger < linger) + if (time_before(fl->linger, linger)) fl->linger = linger; - if (expires < fl->linger) + if (time_before(expires, fl->linger)) expires = fl->linger; - if ((long)(fl->expires - (fl->lastuse+expires)) < 0) + if (time_before(fl->expires, fl->lastuse + expires)) fl->expires = fl->lastuse + expires; return 0; }
@@ -609,8 +613,6 @@ void ip6_flowlabel_init() { - init_timer(&ip6_fl_gc_timer); - ip6_fl_gc_timer.function = ip6_fl_gc; #ifdef CONFIG_PROC_FS create_proc_read_entry("net/ip6_flowlabel", 0, 0, ip6_fl_read_proc, NULL); #endif