s390/cio: fix accidental interrupt enabling during resume

Since commit 9f3d6d7 chsc_get_channel_measurement_chars is called with
interrupts disabled during resume from hibernate. Since this function
used spin_unlock_irq, interrupts have been enabled accidentally. Fix
this by using the irqsave variant.

Since we can't guarantee the IRQ-enablement state for all (future/
external) callers, change the locking in related functions to prevent
similar bugs in the future.

Fixes: 9f3d6d7 ("s390/cio: update measurement characteristics")
Signed-off-by: Sebastian Ott <[e-mail]>
Reviewed-by: Peter Oberparleiter <[e-mail]>
Signed-off-by: Martin Schwidefsky <[e-mail]>

drivers/s390/cio/chsc.c

···
 int chsc_get_ssd_info(struct subchannel_id schid, struct chsc_ssd_info *ssd)
 {
 	struct chsc_ssd_area *ssd_area;
+	unsigned long flags;
 	int ccode;
 	int ret;
 	int i;
 	int mask;
 
-	spin_lock_irq(&chsc_page_lock);
+	spin_lock_irqsave(&chsc_page_lock, flags);
 	memset(chsc_page, 0, PAGE_SIZE);
 	ssd_area = chsc_page;
 	ssd_area->request.length = 0x0010;
···
 			ssd->fla[i] = ssd_area->fla[i];
 	}
 out:
-	spin_unlock_irq(&chsc_page_lock);
+	spin_unlock_irqrestore(&chsc_page_lock, flags);
 	return ret;
 }
 
···
 		u32 fmt : 4;
 		u32 : 16;
 	} __attribute__ ((packed)) *secm_area;
+	unsigned long flags;
 	int ret, ccode;
 
-	spin_lock_irq(&chsc_page_lock);
+	spin_lock_irqsave(&chsc_page_lock, flags);
 	memset(chsc_page, 0, PAGE_SIZE);
 	secm_area = chsc_page;
 	secm_area->request.length = 0x0050;
···
 		CIO_CRW_EVENT(2, "chsc: secm failed (rc=%04x)\n",
 			      secm_area->response.code);
 out:
-	spin_unlock_irq(&chsc_page_lock);
+	spin_unlock_irqrestore(&chsc_page_lock, flags);
 	return ret;
 }
 
···
 
 int chsc_get_channel_measurement_chars(struct channel_path *chp)
 {
+	unsigned long flags;
 	int ccode, ret;
 
 	struct {
···
 	if (!css_chsc_characteristics.scmc || !css_chsc_characteristics.secm)
 		return -EINVAL;
 
-	spin_lock_irq(&chsc_page_lock);
+	spin_lock_irqsave(&chsc_page_lock, flags);
 	memset(chsc_page, 0, PAGE_SIZE);
 	scmc_area = chsc_page;
 	scmc_area->request.length = 0x0010;
···
 	chsc_initialize_cmg_chars(chp, scmc_area->cmcv,
 				  (struct cmg_chars *) &scmc_area->data);
 out:
-	spin_unlock_irq(&chsc_page_lock);
+	spin_unlock_irqrestore(&chsc_page_lock, flags);
 	return ret;
 }
 
···
 int __init
 chsc_determine_css_characteristics(void)
 {
+	unsigned long flags;
 	int result;
 	struct {
 		struct chsc_header request;
···
 		u32 chsc_char[508];
 	} __attribute__ ((packed)) *scsc_area;
 
-	spin_lock_irq(&chsc_page_lock);
+	spin_lock_irqsave(&chsc_page_lock, flags);
 	memset(chsc_page, 0, PAGE_SIZE);
 	scsc_area = chsc_page;
 	scsc_area->request.length = 0x0010;
···
 		CIO_CRW_EVENT(2, "chsc: scsc failed (rc=%04x)\n",
 			      scsc_area->response.code);
 exit:
-	spin_unlock_irq(&chsc_page_lock);
+	spin_unlock_irqrestore(&chsc_page_lock, flags);
 	return result;
 }