From: Harald Freudenberger <freude@linux.ibm.com>
Date: Thu, 21 Jan 2021 16:03:08 +0100
Subject: s390/zcrypt: return EIO when msg retry limit reached
Git-commit: d39fae45c97c67b1b4da04773f2bb5a2f29088c4
Patch-mainline: v5.12-rc1
References: git-fixes

When a msg is retried because the lower ap layer returns -EAGAIN
there is a retry limit (currently 10). When this limit is reached
the last return code from the lower layer is returned, causing
the userspace to get -1 on the ioctl with errno EAGAIN.

This EAGAIN is misleading here. After 10 retry attempts the
userspace should receive a clear failure indication like EINVAL
or EIO or ENODEV. However, the reason why these retries all
fail is unclear. On an invalid message EINVAL would be returned
by the lower layer, and if devices go away or are not available
an ENODEV is seen. So this patch now reworks the retry loops
to return EIO to userspace when the retry limit is reached.

Fixes: 91ffc519c199 ("s390/zcrypt: introduce msg tracking in zcrypt functions")
Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/s390/crypto/zcrypt_api.c |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

--- a/drivers/s390/crypto/zcrypt_api.c
+++ b/drivers/s390/crypto/zcrypt_api.c
@@ -1447,6 +1447,8 @@ static int icarsamodexpo_ioctl(struct ap
 			if (rc == -EAGAIN)
 				tr.again_counter++;
 		} while (rc == -EAGAIN && tr.again_counter < TRACK_AGAIN_MAX);
+	if (rc == -EAGAIN && tr.again_counter >= TRACK_AGAIN_MAX)
+		rc = -EIO;
 	if (rc) {
 		ZCRYPT_DBF(DBF_DEBUG, "ioctl ICARSAMODEXPO rc=%d\n", rc);
 		return rc;
@@ -1490,6 +1492,8 @@ static int icarsacrt_ioctl(struct ap_per
 			if (rc == -EAGAIN)
 				tr.again_counter++;
 		} while (rc == -EAGAIN && tr.again_counter < TRACK_AGAIN_MAX);
+	if (rc == -EAGAIN && tr.again_counter >= TRACK_AGAIN_MAX)
+		rc = -EIO;
 	if (rc) {
 		ZCRYPT_DBF(DBF_DEBUG, "ioctl ICARSACRT rc=%d\n", rc);
 		return rc;
@@ -1533,6 +1537,8 @@ static int zsecsendcprb_ioctl(struct ap_
 			if (rc == -EAGAIN)
 				tr.again_counter++;
 		} while (rc == -EAGAIN && tr.again_counter < TRACK_AGAIN_MAX);
+	if (rc == -EAGAIN && tr.again_counter >= TRACK_AGAIN_MAX)
+		rc = -EIO;
 	if (rc)
 		ZCRYPT_DBF(DBF_DEBUG, "ioctl ZSENDCPRB rc=%d status=0x%x\n",
 			   rc, xcRB.status);
@@ -1577,6 +1583,8 @@ static int zsendep11cprb_ioctl(struct ap
 			if (rc == -EAGAIN)
 				tr.again_counter++;
 		} while (rc == -EAGAIN && tr.again_counter < TRACK_AGAIN_MAX);
+	if (rc == -EAGAIN && tr.again_counter >= TRACK_AGAIN_MAX)
+		rc = -EIO;
 	if (rc)
 		ZCRYPT_DBF(DBF_DEBUG, "ioctl ZSENDEP11CPRB rc=%d\n", rc);
 	if (copy_to_user(uxcrb, &xcrb, sizeof(xcrb)))
@@ -1753,6 +1761,8 @@ static long trans_modexpo32(struct ap_pe
 			if (rc == -EAGAIN)
 				tr.again_counter++;
 		} while (rc == -EAGAIN && tr.again_counter < TRACK_AGAIN_MAX);
+	if (rc == -EAGAIN && tr.again_counter >= TRACK_AGAIN_MAX)
+		rc = -EIO;
 	if (rc)
 		return rc;
 	return put_user(mex64.outputdatalength,
@@ -1804,6 +1814,8 @@ static long trans_modexpo_crt32(struct a
 			if (rc == -EAGAIN)
 				tr.again_counter++;
 		} while (rc == -EAGAIN && tr.again_counter < TRACK_AGAIN_MAX);
+	if (rc == -EAGAIN && tr.again_counter >= TRACK_AGAIN_MAX)
+		rc = -EIO;
 	if (rc)
 		return rc;
 	return put_user(crt64.outputdatalength,
@@ -1874,6 +1886,8 @@ static long trans_xcRB32(struct ap_perms
 			if (rc == -EAGAIN)
 				tr.again_counter++;
 		} while (rc == -EAGAIN && tr.again_counter < TRACK_AGAIN_MAX);
+	if (rc == -EAGAIN && tr.again_counter >= TRACK_AGAIN_MAX)
+		rc = -EIO;
 	xcRB32.reply_control_blk_length = xcRB64.reply_control_blk_length;
 	xcRB32.reply_data_length = xcRB64.reply_data_length;
 	xcRB32.status = xcRB64.status;