From: Jason Gunthorpe <jgg@mellanox.com>
Date: Wed, 25 Jul 2018 21:40:19 -0600
Subject: IB/uverbs: Do not block disassociate during write()
Patch-mainline: v4.19-rc1
Git-commit: a9b66d6453d70ee01f11bdae40d68996cee7474a
References: bsc#1103992 FATE#326009

Now that all the callbacks are safe to run concurrently with
disassociation this test can be eliminated. The ufile core infrastructure
becomes entirely self contained and is not sensitive to disassociation.

Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/infiniband/core/uverbs.h      |    3 +++
 drivers/infiniband/core/uverbs_main.c |   31 ++++++++-----------------------
 2 files changed, 11 insertions(+), 23 deletions(-)

--- a/drivers/infiniband/core/uverbs.h
+++ b/drivers/infiniband/core/uverbs.h
@@ -158,6 +158,9 @@ struct ib_uverbs_file {
 	spinlock_t		uobjects_lock;
 	struct list_head	uobjects;
 
+	u64 uverbs_cmd_mask;
+	u64 uverbs_ex_cmd_mask;
+
 	struct idr		idr;
 	/* spinlock protects write access to idr */
 	spinlock_t		idr_lock;
--- a/drivers/infiniband/core/uverbs_main.c
+++ b/drivers/infiniband/core/uverbs_main.c
@@ -646,13 +646,13 @@ err_put_refs:
 	return filp;
 }
 
-static bool verify_command_mask(struct ib_device *ib_dev,
-				u32 command, bool extended)
+static bool verify_command_mask(struct ib_uverbs_file *ufile, u32 command,
+				bool extended)
 {
 	if (!extended)
-		return ib_dev->uverbs_cmd_mask & BIT_ULL(command);
+		return ufile->uverbs_cmd_mask & BIT_ULL(command);
 
-	return ib_dev->uverbs_ex_cmd_mask & BIT_ULL(command);
+	return ufile->uverbs_ex_cmd_mask & BIT_ULL(command);
 }
 
 static bool verify_command_idx(u32 command, bool extended)
@@ -722,7 +722,6 @@ static ssize_t ib_uverbs_write(struct fi
 {
 	struct ib_uverbs_file *file = filp->private_data;
 	struct ib_uverbs_ex_cmd_hdr ex_hdr;
-	struct ib_device *ib_dev;
 	struct ib_uverbs_cmd_hdr hdr;
 	bool extended;
 	int srcu_key;
@@ -757,24 +756,7 @@ static ssize_t ib_uverbs_write(struct fi
 		return ret;
 
 	srcu_key = srcu_read_lock(&file->device->disassociate_srcu);
-	ib_dev = srcu_dereference(file->device->ib_dev,
-				  &file->device->disassociate_srcu);
-	if (!ib_dev) {
-		ret = -EIO;
-		goto out;
-	}
-
-	/*
-	 * Must be after the ib_dev check, as once the RCU clears ib_dev ==
-	 * NULL means ucontext == NULL
-	 */
-	if (!file->ucontext &&
-	    (command != IB_USER_VERBS_CMD_GET_CONTEXT || extended)) {
-		ret = -EINVAL;
-		goto out;
-	}
-
-	if (!verify_command_mask(ib_dev, command, extended)) {
+	if (!verify_command_mask(file, command, extended)) {
 		ret = -EOPNOTSUPP;
 		goto out;
 	}
@@ -899,6 +881,9 @@ static int ib_uverbs_open(struct inode *
 	mutex_unlock(&dev->lists_mutex);
 	srcu_read_unlock(&dev->disassociate_srcu, srcu_key);
 
+	file->uverbs_cmd_mask = ib_dev->uverbs_cmd_mask;
+	file->uverbs_ex_cmd_mask = ib_dev->uverbs_ex_cmd_mask;
+
 	return nonseekable_open(inode, filp);
 
 err_module: