Patch "s390/dasd: fix diag 0x250 inline assembly" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

    s390/dasd: fix diag 0x250 inline assembly

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:

     s390-dasd-fix-diag-0x250-inline-assembly.patch

and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Heiko Carstens <[email protected]>
Date: Tue, 1 Mar 2016 12:58:06 +0100
Subject: s390/dasd: fix diag 0x250 inline assembly

From: Heiko Carstens <[email protected]>

commit ce0c12b633846a47e103842149a5bac2e5d261ec upstream.

git commit 1ec2772e0c3c ("s390/diag: add a statistic for diagnose calls") added function calls to gather diagnose statistics.

In case of the dasd diag driver the function call was added between a register asm statement which initialized register r2 and the inline assembly itself. The function call clobbers the contents of register r2 and therefore the diag 0x250 call behaves in a more or less random way.

Fix this by extracting the function call into a separate function like we do everywhere else.

---
 drivers/s390/block/dasd_diag.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

@@ -67,7 +67,7 @@ static const u8 DASD_DIAG_CMS1[] = { 0xc
  * and function code cmd.
  * In case of an exception return 3. Otherwise return result of bitwise OR of
  * resulting condition code and DIAG return code. */
-static inline int dia250(void *iob, int cmd)
+static inline int __dia250(void *iob, int cmd)
 {
 	register unsigned long reg2 asm ("2") = (unsigned long) iob;
 	typedef union {

@@ -77,7 +77,6 @@ static inline int dia250(void *iob, int
 	int rc;
 
 	rc = 3;
-	diag_stat_inc(DIAG_STAT_X250);
 	asm volatile(
 		"	diag	2,%2,0x250\n"
 		"0:	ipm	%0\n"

@@ -91,6 +90,12 @@ static inline int dia250(void *iob, int
 	return rc;
 }
 
+static inline int dia250(void *iob, int cmd)
+{
+	diag_stat_inc(DIAG_STAT_X250);
+	return __dia250(iob, cmd);
+}
+
 /* Initialize block I/O to DIAG device using the specified blocksize and
  * block offset. On success, return zero and set end_block to contain the
  * number of blocks on the device minus the specified offset. Return non-zero

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/s390-mm-four-page-table-levels-vs.-fork.patch queue-4.4/s390-dasd-fix-diag-0x250-inline-assembly.patch