linux-kernel - [PATCH] block/aoe: discover_timer: Convert timers to use timer

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Date:   Thu, 2 Nov 2017 16:31:51 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     "Ed L. Cashin" <ed.cashin@....org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] block/aoe: discover_timer: Convert timers to use
 timer_setup()

In preparation for unconditionally passing the struct timer_list pointer to
all timer callbacks, switch to using the new timer_setup() and from_timer()
to pass the timer pointer explicitly.

This refactors the discover_timer to remove the needless locking and
state machine used for synchronizing timer death. Using del_timer_sync()
will already do the right thing.

Cc: Jens Axboe <axboe@...nel.dk>
Cc: "Ed L. Cashin" <ed.cashin@....org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Kees Cook <keescook@...omium.org>
---
 drivers/block/aoe/aoemain.c | 44 ++++++++------------------------------------
 1 file changed, 8 insertions(+), 36 deletions(-)

diff --git a/drivers/block/aoe/aoemain.c b/drivers/block/aoe/aoemain.c
index 4b987c2fefbe..251482066977 100644
--- a/drivers/block/aoe/aoemain.c
+++ b/drivers/block/aoe/aoemain.c
@@ -15,49 +15,19 @@ MODULE_AUTHOR("Sam Hopkins <sah@...aid.com>");
 MODULE_DESCRIPTION("AoE block/char driver for 2.6.2 and newer 2.6 kernels");
 MODULE_VERSION(VERSION);
 
-enum { TINIT, TRUN, TKILL };
+static struct timer_list timer;
 
-static void
-discover_timer(ulong vp)
+static void discover_timer(struct timer_list *t)
 {
-	static struct timer_list t;
-	static volatile ulong die;
-	static spinlock_t lock;
-	ulong flags;
-	enum { DTIMERTICK = HZ * 60 }; /* one minute */
-
-	switch (vp) {
-	case TINIT:
-		init_timer(&t);
-		spin_lock_init(&lock);
-		t.data = TRUN;
-		t.function = discover_timer;
-		die = 0;
-	case TRUN:
-		spin_lock_irqsave(&lock, flags);
-		if (!die) {
-			t.expires = jiffies + DTIMERTICK;
-			add_timer(&t);
-		}
-		spin_unlock_irqrestore(&lock, flags);
-
-		aoecmd_cfg(0xffff, 0xff);
-		return;
-	case TKILL:
-		spin_lock_irqsave(&lock, flags);
-		die = 1;
-		spin_unlock_irqrestore(&lock, flags);
+	mod_timer(t, jiffies + HZ * 60); /* one minute */
 
-		del_timer_sync(&t);
-	default:
-		return;
-	}
+	aoecmd_cfg(0xffff, 0xff);
 }
 
 static void
 aoe_exit(void)
 {
-	discover_timer(TKILL);
+	del_timer_sync(&timer);
 
 	aoenet_exit();
 	unregister_blkdev(AOE_MAJOR, DEVICE_NAME);
@@ -93,7 +63,9 @@ aoe_init(void)
 		goto blkreg_fail;
 	}
 	printk(KERN_INFO "aoe: AoE v%s initialised.\n", VERSION);
-	discover_timer(TINIT);
+
+	timer_setup(&timer, discover_timer, 0);
+	discover_timer(&timer);
 	return 0;
  blkreg_fail:
 	aoecmd_exit();
-- 
2.7.4


-- 
Kees Cook
Pixel Security