From 08a8a0c59e54f7eb80897c1e77efa4a541d11008 Mon Sep 17 00:00:00 2001 From: Josef 'Jeff' Sipek Date: Thu, 17 Apr 2008 07:45:56 +0200 Subject: [PATCH] [S390] dasd: fix double elevator_exit call when deadline iosched fails to load I compiled the kernel without deadline, and the dasd code exits the old scheduler (CFQ), fails to load the new one (deadline), and then things just hang - with one of these (sorry about the weird chars - I copy & pasted it from a 3270 console): dasd(eckd): 0.0.0151: 3390/0A(CU:3990/01) Cyl:3338 Head:15 Sec:224 ------------ cut here ------------ Badness at kernel/mutex.c:134 Modules linked in: dasd_eckd_mod dasd_mod CPU: 0 Not tainted 2.6.25-rc3 #9 Process exe (pid: 538, task: 000000000d172000, ksp: 000000000d21ef88) Krnl PSW : 0404000180000000 000000000022fb5c (mutex_lock_nested+0x2a4/0x2cc) R:0 T:1 IO:0 EX:0 Key:0 M:1 W:0 P:0 AS:0 CC:0 PM:0 EA:3 Krnl GPRS: 0000000000024218 000000000076fc78 0000000000000000 000000000000000f 000000000022f92e 0000000000449898 000000000f921c00 000003e000162590 00000000001539c4 000000000d172000 070000007fffffff 000000000d21f400 000000000f8f2560 00000000002413f8 000000000022fb44 000000000d21f400 Krnl Code: 000000000022fb50: bf2f1000 icm %r2,15,0(%r1) 000000000022fb54: a774fef6 brc 7,22f940 000000000022fb58: a7f40001 brc 15,22fb5a >000000000022fb5c: a7f4fef2 brc 15,22f940 000000000022fb60: c0e5fffa112a brasl %r14,171db4 000000000022fb66: 1222 ltr %r2,%r2 000000000022fb68: a784fedb brc 8,22f91e 000000000022fb6c: c010002a0086 larl %r1,76fc78 Call Trace: (<000000000022f92e> mutex_lock_nested+0x76/0x2cc) <00000000001539c4> elevator_exit+0x38/0x80 <0000000000156ffe> blk_cleanup_queue+0x62/0x7c <000003e0001d5414> dasd_change_state+0xe0/0x8ec <000003e0001d5cae> dasd_set_target_state+0x8e/0x9c <000003e0001d5f74> dasd_generic_set_online+0x160/0x284 <000003e00011e83a> dasd_eckd_set_online+0x2e/0x40 <0000000000199bf4> ccw_device_set_online+0x170/0x2c0 <0000000000199d9e> online_store_recog_and_online+0x5a/0x14c <000000000019a08a> online_store+0xbe/0x2ec <000000000018456c> dev_attr_store+0x38/0x58 <000000000010efbc> sysfs_write_file+0x130/0x190 <00000000000af582> vfs_write+0xb2/0x160 <00000000000afc7c> sys_write+0x54/0x9c <0000000000025e16> sys32_write+0x2e/0x50 <0000000000024218> sysc_noemu+0x10/0x16 <0000000077e82bd2> 0x77e82bd2 Set elevator pointer to NULL in order to avoid double elevator_exit calls when elevator_init call for deadline iosched fails. Also make sure the dasd device driver depends on IOSCHED_DEADLINE so the default IO scheduler of the dasd driver is present. Signed-off-by: Josef 'Jeff' Sipek Signed-off-by: Martin Schwidefsky Signed-off-by: Heiko Carstens --- drivers/s390/block/Kconfig | 1 + drivers/s390/block/dasd.c | 1 + 2 files changed, 2 insertions(+) diff --git a/drivers/s390/block/Kconfig b/drivers/s390/block/Kconfig index e879b212cf..07883197f4 100644 --- a/drivers/s390/block/Kconfig +++ b/drivers/s390/block/Kconfig @@ -20,6 +20,7 @@ config DCSSBLK config DASD tristate "Support for DASD devices" depends on CCW && BLOCK + select IOSCHED_DEADLINE help Enable this option if you want to access DASDs directly utilizing S/390s channel subsystem commands. This is necessary for running diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c index ccf46c96ad..54f686d2c6 100644 --- a/drivers/s390/block/dasd.c +++ b/drivers/s390/block/dasd.c @@ -1956,6 +1956,7 @@ static int dasd_alloc_queue(struct dasd_block *block) block->request_queue->queuedata = block; elevator_exit(block->request_queue->elevator); + block->request_queue->elevator = NULL; rc = elevator_init(block->request_queue, "deadline"); if (rc) { blk_cleanup_queue(block->request_queue); -- 2.39.5