linux-kernel - [PATCH] RDMA/hfi1: Convert from atomic_t to refcount_t on hfi1_devdata->user

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Date:   Mon, 19 Jul 2021 14:00:53 +0800
From:   Xiyu Yang <xiyuyang19@...an.edu.cn>
To:     Mike Marciniszyn <mike.marciniszyn@...nelisnetworks.com>,
        Dennis Dalessandro <dennis.dalessandro@...nelisnetworks.com>,
        Doug Ledford <dledford@...hat.com>,
        Jason Gunthorpe <jgg@...pe.ca>, linux-rdma@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     yuanxzhang@...an.edu.cn, Xiyu Yang <xiyuyang19@...an.edu.cn>,
        Xin Tan <tanxin.ctf@...il.com>
Subject: [PATCH] RDMA/hfi1: Convert from atomic_t to refcount_t on hfi1_devdata->user_refcount

refcount_t type and corresponding API can protect refcounters from
accidental underflow and overflow and further use-after-free situations.

Signed-off-by: Xiyu Yang <xiyuyang19@...an.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@...il.com>
---
 drivers/infiniband/hw/hfi1/chip.c     | 2 +-
 drivers/infiniband/hw/hfi1/file_ops.c | 6 +++---
 drivers/infiniband/hw/hfi1/hfi.h      | 3 ++-
 drivers/infiniband/hw/hfi1/init.c     | 2 +-
 4 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/infiniband/hw/hfi1/chip.c b/drivers/infiniband/hw/hfi1/chip.c
index c97544638367..50ffb8244625 100644
--- a/drivers/infiniband/hw/hfi1/chip.c
+++ b/drivers/infiniband/hw/hfi1/chip.c
@@ -15336,7 +15336,7 @@ int hfi1_init_dd(struct hfi1_devdata *dd)
 	init_completion(&dd->user_comp);
 
 	/* The user refcount starts with one to inidicate an active device */
-	atomic_set(&dd->user_refcount, 1);
+	refcount_set(&dd->user_refcount, 1);
 
 	goto bail;
 
diff --git a/drivers/infiniband/hw/hfi1/file_ops.c b/drivers/infiniband/hw/hfi1/file_ops.c
index 955c3637980e..6dbfb794c255 100644
--- a/drivers/infiniband/hw/hfi1/file_ops.c
+++ b/drivers/infiniband/hw/hfi1/file_ops.c
@@ -194,7 +194,7 @@ static int hfi1_file_open(struct inode *inode, struct file *fp)
 	if (!((dd->flags & HFI1_PRESENT) && dd->kregbase1))
 		return -EINVAL;
 
-	if (!atomic_inc_not_zero(&dd->user_refcount))
+	if (!refcount_inc_not_zero(&dd->user_refcount))
 		return -ENXIO;
 
 	/* The real work is performed later in assign_ctxt() */
@@ -213,7 +213,7 @@ static int hfi1_file_open(struct inode *inode, struct file *fp)
 nomem:
 	kfree(fd);
 	fp->private_data = NULL;
-	if (atomic_dec_and_test(&dd->user_refcount))
+	if (refcount_dec_and_test(&dd->user_refcount))
 		complete(&dd->user_comp);
 	return -ENOMEM;
 }
@@ -711,7 +711,7 @@ static int hfi1_file_close(struct inode *inode, struct file *fp)
 	deallocate_ctxt(uctxt);
 done:
 
-	if (atomic_dec_and_test(&dd->user_refcount))
+	if (refcount_dec_and_test(&dd->user_refcount))
 		complete(&dd->user_comp);
 
 	cleanup_srcu_struct(&fdata->pq_srcu);
diff --git a/drivers/infiniband/hw/hfi1/hfi.h b/drivers/infiniband/hw/hfi1/hfi.h
index 31664f43c27f..6cf03d16a495 100644
--- a/drivers/infiniband/hw/hfi1/hfi.h
+++ b/drivers/infiniband/hw/hfi1/hfi.h
@@ -48,6 +48,7 @@
  *
  */
 
+#include <linux/refcount.h>
 #include <linux/interrupt.h>
 #include <linux/pci.h>
 #include <linux/dma-mapping.h>
@@ -1384,7 +1385,7 @@ struct hfi1_devdata {
 	/* Number of verbs contexts which have disabled ASPM */
 	atomic_t aspm_disabled_cnt;
 	/* Keeps track of user space clients */
-	atomic_t user_refcount;
+	refcount_t user_refcount;
 	/* Used to wait for outstanding user space clients before dev removal */
 	struct completion user_comp;
 
diff --git a/drivers/infiniband/hw/hfi1/init.c b/drivers/infiniband/hw/hfi1/init.c
index 0986aa065418..0b2e19a335c5 100644
--- a/drivers/infiniband/hw/hfi1/init.c
+++ b/drivers/infiniband/hw/hfi1/init.c
@@ -1752,7 +1752,7 @@ static void wait_for_clients(struct hfi1_devdata *dd)
 	 * Remove the device init value and complete the device if there is
 	 * no clients or wait for active clients to finish.
 	 */
-	if (atomic_dec_and_test(&dd->user_refcount))
+	if (refcount_dec_and_test(&dd->user_refcount))
 		complete(&dd->user_comp);
 
 	wait_for_completion(&dd->user_comp);
-- 
2.7.4