s390/crypto: Extend protected key conversion retry loop

CI runs show that the protected key conversion retry loop
runs into timeout if a master key change was initiated on
the addressed crypto resource shortly before the conversion
request.

This patch extends the retry logic to run in total 5 attempts
with increasing delay (200, 400, 800 and 1600 ms) in case of
a busy card.

Signed-off-by: Harald Freudenberger <[email protected]>
Reviewed-by: Ingo Franzki <[email protected]>
Signed-off-by: Heiko Carstens <[email protected]>

Author: hfreude

arch/s390/crypto/paes_s390.c

@@ -199,8 +199,11 @@ static inline int convert_key(const u8 *key, unsigned int keylen,
 
 	pk->len = sizeof(pk->protkey);
 
-	/* try three times in case of busy card */
-	for (rc = -EIO, i = 0; rc && i < 3; i++) {
+	/*
+	 * In case of a busy card retry with increasing delay
+	 * of 200, 400, 800 and 1600 ms - in total 3 s.
+	 */
+	for (rc = -EIO, i = 0; rc && i < 5; i++) {
 		if (rc == -EBUSY && msleep_interruptible((1 << i) * 100)) {
 			rc = -EINTR;
 			goto out;