From a41a11b4009580edb6e2b4c76e5e2ee303f87157 Mon Sep 17 00:00:00 2001 From: Gerald Schaefer Date: Thu, 27 Oct 2022 16:19:38 +0200 Subject: s390/dcssblk: fix deadlock when adding a DCSS After the rework from commit 1ebe2e5f9d68 ("block: remove GENHD_FL_EXT_DEVT"), when calling device_add_disk(), dcssblk will end up in disk_scan_partitions(), and not break out early w/o GENHD_FL_NO_PART. This will trigger implicit open/release via blkdev_get/put_whole() later. dcssblk_release() will then deadlock on dcssblk_devices_sem semaphore, which is already held from dcssblk_add_store() when calling device_add_disk(). dcssblk does not support partitions (DCSSBLK_MINORS_PER_DISK == 1), and never scanned partitions before. Therefore restore the previous behavior, and explicitly disallow partition scanning by setting the GENHD_FL_NO_PART flag. This will also prevent this deadlock scenario. Fixes: 1ebe2e5f9d68 ("block: remove GENHD_FL_EXT_DEVT") Cc: # 5.17+ Signed-off-by: Gerald Schaefer Acked-by: Heiko Carstens Signed-off-by: Alexander Gordeev --- drivers/s390/block/dcssblk.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c index 93b80da60277..b392b9f5482e 100644 --- a/drivers/s390/block/dcssblk.c +++ b/drivers/s390/block/dcssblk.c @@ -636,6 +636,7 @@ dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char dev_info->gd->minors = DCSSBLK_MINORS_PER_DISK; dev_info->gd->fops = &dcssblk_devops; dev_info->gd->private_data = dev_info; + dev_info->gd->flags |= GENHD_FL_NO_PART; blk_queue_logical_block_size(dev_info->gd->queue, 4096); blk_queue_flag_set(QUEUE_FLAG_DAX, dev_info->gd->queue); -- cgit v1.2.3 From e3c11025bcd2142a61abe5806b2f86a0e78118df Mon Sep 17 00:00:00 2001 From: Vasily Gorbik Date: Fri, 4 Nov 2022 12:06:47 +0100 Subject: s390: avoid using global register for current_stack_pointer Commit 30de14b1884b ("s390: current_stack_pointer shouldn't be a function") made current_stack_pointer a global register variable like on many other architectures. Unfortunately on s390 it uncovers old gcc bug which is fixed only since gcc-9.1 [gcc commit 3ad7fed1cc87 ("S/390: Fix PR89775. Stackpointer save/restore instructions removed")] and backported to gcc-8.4 and later. Due to this bug gcc versions prior to 8.4 generate broken code which leads to stack corruptions. Current minimal gcc version required to build the kernel is declared as 5.1. It is not possible to fix all old gcc versions, so work around this problem by avoiding using global register variable for current_stack_pointer. Fixes: 30de14b1884b ("s390: current_stack_pointer shouldn't be a function") Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Alexander Gordeev --- arch/s390/include/asm/processor.h | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h index 87be3e855bf7..c907f747d2a0 100644 --- a/arch/s390/include/asm/processor.h +++ b/arch/s390/include/asm/processor.h @@ -199,7 +199,16 @@ unsigned long __get_wchan(struct task_struct *p); /* Has task runtime instrumentation enabled ? */ #define is_ri_task(tsk) (!!(tsk)->thread.ri_cb) -register unsigned long current_stack_pointer asm("r15"); +/* avoid using global register due to gcc bug in versions < 8.4 */ +#define current_stack_pointer (__current_stack_pointer()) + +static __always_inline unsigned long __current_stack_pointer(void) +{ + unsigned long sp; + + asm volatile("lgr %0,15" : "=d" (sp)); + return sp; +} static __always_inline unsigned short stap(void) { -- cgit v1.2.3