3 files changed, 72 insertions, 41 deletions

diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
index 8e872951c07b..bc61ea18e88d 100644
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -939,5 +939,5 @@ subsys_initcall_sync(pci_base_init);
 void zpci_rescan(void)
 {
 	if (zpci_is_enabled())
-		clp_rescan_pci_devices_simple();
+		clp_rescan_pci_devices_simple(NULL);
 }
diff --git a/arch/s390/pci/pci_clp.c b/arch/s390/pci/pci_clp.c
index 4c613e569fe0..0d3d8f170ea4 100644
--- a/arch/s390/pci/pci_clp.c
+++ b/arch/s390/pci/pci_clp.c
@@ -240,12 +240,14 @@ error:
 }
 
 /*
- * Enable/Disable a given PCI function defined by its function handle.
+ * Enable/Disable a given PCI function and update its function handle if
+ * necessary
  */
-static int clp_set_pci_fn(u32 *fh, u8 nr_dma_as, u8 command)
+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)
@@ -256,7 +258,7 @@ static int clp_set_pci_fn(u32 *fh, u8 nr_dma_as, u8 command)
 		rrb->request.hdr.len = sizeof(rrb->request);
 		rrb->request.hdr.cmd = CLP_SET_PCI_FN;
 		rrb->response.hdr.len = sizeof(rrb->response);
-		rrb->request.fh = *fh;
+		rrb->request.fh = zdev->fh;
 		rrb->request.oc = command;
 		rrb->request.ndas = nr_dma_as;
 
@@ -269,12 +271,17 @@ static int clp_set_pci_fn(u32 *fh, u8 nr_dma_as, u8 command)
 		}
 	} while (rrb->response.hdr.rsp == CLP_RC_SETPCIFN_BUSY);
 
-	if (!rc && rrb->response.hdr.rsp == CLP_RC_OK)
-		*fh = rrb->response.fh;
-	else {
+	if (rc || rrb->response.hdr.rsp != CLP_RC_OK) {
 		zpci_err("Set PCI FN:\n");
 		zpci_err_clp(rrb->response.hdr.rsp, rc);
-		rc = -EIO;
+	}
+
+	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) {
+		/* Function is already in desired state - update handle */
+		rc = clp_rescan_pci_devices_simple(&fid);
 	}
 	clp_free_block(rrb);
 	return rc;
@@ -282,18 +289,17 @@ static int clp_set_pci_fn(u32 *fh, u8 nr_dma_as, u8 command)
 
 int clp_enable_fh(struct zpci_dev *zdev, u8 nr_dma_as)
 {
-	u32 fh = zdev->fh;
 	int rc;
 
-	rc = clp_set_pci_fn(&fh, nr_dma_as, CLP_SET_ENABLE_PCI_FN);
-	zpci_dbg(3, "ena fid:%x, fh:%x, rc:%d\n", zdev->fid, fh, rc);
+	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;
 
-	zdev->fh = fh;
 	if (zpci_use_mio(zdev)) {
-		rc = clp_set_pci_fn(&fh, nr_dma_as, CLP_SET_ENABLE_MIO);
-		zpci_dbg(3, "ena mio fid:%x, fh:%x, rc:%d\n", zdev->fid, fh, rc);
+		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);
 	}
@@ -309,11 +315,8 @@ int clp_disable_fh(struct zpci_dev *zdev)
 	if (!zdev_enabled(zdev))
 		return 0;
 
-	rc = clp_set_pci_fn(&fh, 0, CLP_SET_DISABLE_PCI_FN);
+	rc = clp_set_pci_fn(zdev, 0, CLP_SET_DISABLE_PCI_FN);
 	zpci_dbg(3, "dis fid:%x, fh:%x, rc:%d\n", zdev->fid, fh, rc);
-	if (!rc)
-		zdev->fh = fh;
-
 	return rc;
 }
 
@@ -370,10 +373,14 @@ static void __clp_add(struct clp_fh_list_entry *entry, void *data)
 static void __clp_update(struct clp_fh_list_entry *entry, void *data)
 {
 	struct zpci_dev *zdev;
+	u32 *fid = data;
 
 	if (!entry->vendor_id)
 		return;
 
+	if (fid && *fid != entry->fid)
+		return;
+
 	zdev = get_zdev_by_fid(entry->fid);
 	if (!zdev)
 		return;
@@ -413,7 +420,10 @@ int clp_rescan_pci_devices(void)
 	return rc;
 }
 
-int clp_rescan_pci_devices_simple(void)
+/* Rescan PCI functions and refresh function handles. If fid is non-NULL only
+ * refresh the handle of the function matching @fid
+ */
+int clp_rescan_pci_devices_simple(u32 *fid)
 {
 	struct clp_req_rsp_list_pci *rrb;
 	int rc;
@@ -422,7 +432,7 @@ int clp_rescan_pci_devices_simple(void)
 	if (!rrb)
 		return -ENOMEM;
 
-	rc = clp_list_pci(rrb, NULL, __clp_update);
+	rc = clp_list_pci(rrb, fid, __clp_update);
 
 	clp_free_block(rrb);
 	return rc;
diff --git a/arch/s390/pci/pci_sysfs.c b/arch/s390/pci/pci_sysfs.c
index a433ba01a317..215f17437a4f 100644
--- a/arch/s390/pci/pci_sysfs.c
+++ b/arch/s390/pci/pci_sysfs.c
@@ -13,6 +13,8 @@
 #include <linux/stat.h>
 #include <linux/pci.h>
 
+#include "../../../drivers/pci/pci.h"
+
 #include <asm/sclp.h>
 
 #define zpci_attr(name, fmt, member)					\
@@ -49,31 +51,50 @@ static DEVICE_ATTR_RO(mio_enabled);
 static ssize_t recover_store(struct device *dev, struct device_attribute *attr,
 			     const char *buf, size_t count)
 {
+	struct kernfs_node *kn;
 	struct pci_dev *pdev = to_pci_dev(dev);
 	struct zpci_dev *zdev = to_zpci(pdev);
-	int ret;
-
-	if (!device_remove_file_self(dev, attr))
-		return count;
-
+	int ret = 0;
+
+	/* Can't use device_remove_self() here as that would lead us to lock
+	 * the pci_rescan_remove_lock while holding the device' kernfs lock.
+	 * This would create a possible deadlock with disable_slot() which is
+	 * not directly protected by the device' kernfs lock but takes it
+	 * during the device removal which happens under
+	 * pci_rescan_remove_lock.
+	 *
+	 * This is analogous to sdev_store_delete() in
+	 * drivers/scsi/scsi_sysfs.c
+	 */
+	kn = sysfs_break_active_protection(&dev->kobj, &attr->attr);
+	WARN_ON_ONCE(!kn);
+	/* device_remove_file() serializes concurrent calls ignoring all but
+	 * the first
+	 */
+	device_remove_file(dev, attr);
+
+	/* A concurrent call to recover_store() may slip between
+	 * sysfs_break_active_protection() and the sysfs file removal.
+	 * Once it unblocks from pci_lock_rescan_remove() the original pdev
+	 * will already be removed.
+	 */
 	pci_lock_rescan_remove();
-	pci_stop_and_remove_bus_device(pdev);
-	ret = zpci_disable_device(zdev);
-	if (ret)
-		goto error;
-
-	ret = zpci_enable_device(zdev);
-	if (ret)
-		goto error;
-
-	pci_rescan_bus(zdev->bus);
+	if (pci_dev_is_added(pdev)) {
+		pci_stop_and_remove_bus_device(pdev);
+		ret = zpci_disable_device(zdev);
+		if (ret)
+			goto out;
+
+		ret = zpci_enable_device(zdev);
+		if (ret)
+			goto out;
+		pci_rescan_bus(zdev->bus);
+	}
+out:
 	pci_unlock_rescan_remove();
-
-	return count;
-
-error:
-	pci_unlock_rescan_remove();
-	return ret;
+	if (kn)
+		sysfs_unbreak_active_protection(kn);
+	return ret ? ret : count;
 }
 static DEVICE_ATTR_WO(recover);