From b9732ca1cb2c18129d2f984b8de02db141b7b830 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Mon, 14 Jul 2008 09:57:28 +0200 Subject: [S390] sclp: fix possible deadlock on cpu rescan. smp_rescan_cpus() calls get_online_cpus() from a multithreaded workqueue context. This may deadlock. This is the same bug as in arch/s390/kernel/topology.c. This patch can be reverted as soon as Oleg's patch gets merged. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- drivers/s390/char/sclp_config.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) (limited to 'drivers/s390/char/sclp_config.c') diff --git a/drivers/s390/char/sclp_config.c b/drivers/s390/char/sclp_config.c index ad05a87bc480..7c9b39cee595 100644 --- a/drivers/s390/char/sclp_config.c +++ b/drivers/s390/char/sclp_config.c @@ -8,6 +8,7 @@ #include #include #include +#include #include #include #include @@ -40,9 +41,19 @@ static void sclp_cpu_capability_notify(struct work_struct *work) put_online_cpus(); } -static void __ref sclp_cpu_change_notify(struct work_struct *work) +static int sclp_cpu_kthread(void *data) { smp_rescan_cpus(); + return 0; +} + +static void __ref sclp_cpu_change_notify(struct work_struct *work) +{ + /* Can't call smp_rescan_cpus() from workqueue context since it may + * deadlock in case of cpu hotplug. So we have to create a kernel + * thread in order to call it. + */ + kthread_run(sclp_cpu_kthread, NULL, "cpu_rescan"); } static void sclp_conf_receiver_fn(struct evbuf_header *evbuf) -- cgit v1.2.3 From a12c53f4fa759b59654b6d5f21eb4070cd45cd54 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Mon, 14 Jul 2008 09:59:28 +0200 Subject: [S390] Cleanup sclp printk messages. Signed-off-by: Martin Schwidefsky Signed-off-by: Heiko Carstens --- drivers/s390/char/sclp_config.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) (limited to 'drivers/s390/char/sclp_config.c') diff --git a/drivers/s390/char/sclp_config.c b/drivers/s390/char/sclp_config.c index 7c9b39cee595..fff4ff485d9b 100644 --- a/drivers/s390/char/sclp_config.c +++ b/drivers/s390/char/sclp_config.c @@ -85,10 +85,8 @@ static int __init sclp_conf_init(void) INIT_WORK(&sclp_cpu_change_work, sclp_cpu_change_notify); rc = sclp_register(&sclp_conf_register); - if (rc) { - printk(KERN_ERR TAG "failed to register (%d).\n", rc); + if (rc) return rc; - } if (!(sclp_conf_register.sclp_send_mask & EVTYP_CONFMGMDATA_MASK)) { printk(KERN_WARNING TAG "no configuration management.\n"); -- cgit v1.2.3 From fc7e1e4b1ca69109d0f694e47ef2328dcb0ebe6e Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Fri, 1 Aug 2008 16:39:23 +0200 Subject: [S390] dont use kthread for smp_rescan_cpus(). Since git commit 3da1c84c00c7e5fa8348336bd8c342f9128b0f14 "workqueues: make get_online_cpus() useable for work->func()" it is safe to call get_online_cpus() from workqueue context. So remove the kthread workaround again. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- drivers/s390/char/sclp_config.c | 13 +------------ 1 file changed, 1 insertion(+), 12 deletions(-) (limited to 'drivers/s390/char/sclp_config.c') diff --git a/drivers/s390/char/sclp_config.c b/drivers/s390/char/sclp_config.c index fff4ff485d9b..4cebd6ee6d27 100644 --- a/drivers/s390/char/sclp_config.c +++ b/drivers/s390/char/sclp_config.c @@ -8,7 +8,6 @@ #include #include #include -#include #include #include #include @@ -41,19 +40,9 @@ static void sclp_cpu_capability_notify(struct work_struct *work) put_online_cpus(); } -static int sclp_cpu_kthread(void *data) -{ - smp_rescan_cpus(); - return 0; -} - static void __ref sclp_cpu_change_notify(struct work_struct *work) { - /* Can't call smp_rescan_cpus() from workqueue context since it may - * deadlock in case of cpu hotplug. So we have to create a kernel - * thread in order to call it. - */ - kthread_run(sclp_cpu_kthread, NULL, "cpu_rescan"); + smp_rescan_cpus(); } static void sclp_conf_receiver_fn(struct evbuf_header *evbuf) -- cgit v1.2.3