s390 updates for 6.1-rc6

- Fix deadlock in discontiguous saved segments (DCSS) block device
   driver. When adding a disk and scanning partitions the scan would
   not break out early without a missed flag.
 
 - Avoid using global register variable for current_stack_pointer
   due to an old bug in gcc versions prior to gcc-8.4. Due to this
   bug a broken code is generated, which leads to stack corruptions.
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Merge tag 's390-6.1-5' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

Pull s390 fixes from Alexander Gordeev:

 - Fix deadlock in discontiguous saved segments (DCSS) block device
   driver. When adding a disk and scanning partitions the scan would not
   break out early without a missed flag.

 - Avoid using global register variable for current_stack_pointer due to
   an old bug in gcc versions prior to gcc-8.4. Due to this bug a broken
   code is generated, which leads to stack corruptions.

* tag 's390-6.1-5' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390: avoid using global register for current_stack_pointer
  s390/dcssblk: fix deadlock when adding a DCSS

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)
 {

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);