linux-kernel - [PATCH AUTOSEL 5.14 43/47] s390/pci: fix misleading rc in clp_set_pci

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Message-Id: <20210906011951.928679-43-sashal@kernel.org>
Date:   Sun,  5 Sep 2021 21:19:47 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Niklas Schnelle <schnelle@...ux.ibm.com>,
        Matthew Rosato <mjrosato@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Sasha Levin <sashal@...nel.org>, linux-s390@...r.kernel.org
Subject: [PATCH AUTOSEL 5.14 43/47] s390/pci: fix misleading rc in clp_set_pci_fn()

From: Niklas Schnelle <schnelle@...ux.ibm.com>

[ Upstream commit f7addcdd527a6dddfebe20c358b87bdb95624612 ]

Currently clp_set_pci_fn() always returns 0 as long as the CLP request
itself succeeds even if the operation itself returns a response code
other than CLP_RC_OK or CLP_RC_SETPCIFN_ALRDY. This is highly misleading
because calling code assumes that a zero rc means that the operation was
successful.

Fix this by returning the response code or cc on failure with the
exception of the special handling for CLP_RC_SETPCIFN_ALRDY. Also let's
not assume that the returned function handle for CLP_RC_SETPCIFN_ALRDY
is 0, we don't need it anyway.

Reviewed-by: Matthew Rosato <mjrosato@...ux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@...ux.ibm.com>
Signed-off-by: Heiko Carstens <hca@...ux.ibm.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/s390/pci/pci.c     |  7 ++++---
 arch/s390/pci/pci_clp.c | 33 ++++++++++++++++-----------------
 2 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
index 8fcb7ecb7225..77cd965cffef 100644
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -661,9 +661,10 @@ int zpci_enable_device(struct zpci_dev *zdev)
 {
 	int rc;
 
-	rc = clp_enable_fh(zdev, ZPCI_NR_DMA_SPACES);
-	if (rc)
+	if (clp_enable_fh(zdev, ZPCI_NR_DMA_SPACES)) {
+		rc = -EIO;
 		goto out;
+	}
 
 	rc = zpci_dma_init_device(zdev);
 	if (rc)
@@ -684,7 +685,7 @@ int zpci_disable_device(struct zpci_dev *zdev)
 	 * The zPCI function may already be disabled by the platform, this is
 	 * detected in clp_disable_fh() which becomes a no-op.
 	 */
-	return clp_disable_fh(zdev);
+	return clp_disable_fh(zdev) ? -EIO : 0;
 }
 
 /**
diff --git a/arch/s390/pci/pci_clp.c b/arch/s390/pci/pci_clp.c
index d3331596ddbe..0a0e8b8293be 100644
--- a/arch/s390/pci/pci_clp.c
+++ b/arch/s390/pci/pci_clp.c
@@ -213,15 +213,19 @@ int clp_query_pci_fn(struct zpci_dev *zdev)
 }
 
 static int clp_refresh_fh(u32 fid);
-/*
- * Enable/Disable a given PCI function and update its function handle if
- * necessary
+/**
+ * clp_set_pci_fn() - Execute a command on a PCI function
+ * @zdev: Function that will be affected
+ * @nr_dma_as: DMA address space number
+ * @command: The command code to execute
+ *
+ * Returns: 0 on success, < 0 for Linux errors (e.g. -ENOMEM), and
+ * > 0 for non-success platform responses
  */
 static int clp_set_pci_fn(struct zpci_dev *zdev, u8 nr_dma_as, u8 command)
 {
 	struct clp_req_rsp_set_pci *rrb;
 	int rc, retries = 100;
-	u32 fid = zdev->fid;
 
 	rrb = clp_alloc_block(GFP_KERNEL);
 	if (!rrb)
@@ -245,17 +249,16 @@ static int clp_set_pci_fn(struct zpci_dev *zdev, u8 nr_dma_as, u8 command)
 		}
 	} while (rrb->response.hdr.rsp == CLP_RC_SETPCIFN_BUSY);
 
-	if (rc || rrb->response.hdr.rsp != CLP_RC_OK) {
-		zpci_err("Set PCI FN:\n");
-		zpci_err_clp(rrb->response.hdr.rsp, rc);
-	}
-
 	if (!rc && rrb->response.hdr.rsp == CLP_RC_OK) {
 		zdev->fh = rrb->response.fh;
-	} else if (!rc && rrb->response.hdr.rsp == CLP_RC_SETPCIFN_ALRDY &&
-			rrb->response.fh == 0) {
+	} else if (!rc && rrb->response.hdr.rsp == CLP_RC_SETPCIFN_ALRDY) {
 		/* Function is already in desired state - update handle */
-		rc = clp_refresh_fh(fid);
+		rc = clp_refresh_fh(zdev->fid);
+	} else {
+		zpci_err("Set PCI FN:\n");
+		zpci_err_clp(rrb->response.hdr.rsp, rc);
+		if (!rc)
+			rc = rrb->response.hdr.rsp;
 	}
 	clp_free_block(rrb);
 	return rc;
@@ -301,17 +304,13 @@ int clp_enable_fh(struct zpci_dev *zdev, u8 nr_dma_as)
 
 	rc = clp_set_pci_fn(zdev, nr_dma_as, CLP_SET_ENABLE_PCI_FN);
 	zpci_dbg(3, "ena fid:%x, fh:%x, rc:%d\n", zdev->fid, zdev->fh, rc);
-	if (rc)
-		goto out;
-
-	if (zpci_use_mio(zdev)) {
+	if (!rc && zpci_use_mio(zdev)) {
 		rc = clp_set_pci_fn(zdev, nr_dma_as, CLP_SET_ENABLE_MIO);
 		zpci_dbg(3, "ena mio fid:%x, fh:%x, rc:%d\n",
 				zdev->fid, zdev->fh, rc);
 		if (rc)
 			clp_disable_fh(zdev);
 	}
-out:
 	return rc;
 }
 
-- 
2.30.2