From: Ivan Priest <i.priest@samsung.com>
Date: Thu, 2 May 2019 16:16:05 +0000 (+0100)
Subject: [NEUS7920-477] wlbt: prevent simultaneous gdb monitor clients
X-Git-Tag: MMI-QSAS30.62-33-3~861
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=8d05e2586a8f483b93ba48d573b64260cc13fcc9;p=GitHub%2FMotorolaMobilityLLC%2Fkernel-slsi.git

[NEUS7920-477] wlbt: prevent simultaneous gdb monitor clients

No more than one gdb client allowed per node at a time.
Multiple mmap clients are permitted as they are read only

Change-Id: I9e734c776ea13479c9191f6f8eca55ac15b00a3e
SCSC-Bug-Id: SSB-52259
Signed-off-by: Ivan Priest <i.priest@samsung.com>
---

diff --git a/drivers/misc/samsung/scsc/mx_mmap.c b/drivers/misc/samsung/scsc/mx_mmap.c
index 72caddcddc01..10b32f5636c4 100644
--- a/drivers/misc/samsung/scsc/mx_mmap.c
+++ b/drivers/misc/samsung/scsc/mx_mmap.c
@@ -11,6 +11,7 @@
 #include <linux/poll.h>
 
 #include <linux/kernel.h>
+#include <linux/bitops.h>
 #include <linux/slab.h>
 #include <linux/fs.h>
 #include <linux/errno.h>
@@ -67,6 +68,8 @@ struct mx_mmap_dev {
 	struct kfifo         fifo;
 	/* Associated read_wait queue.*/
 	wait_queue_head_t    read_wait;
+	/* User count */
+	volatile unsigned long lock;
 };
 
 /**
@@ -150,6 +153,11 @@ int mx_gdb_open(struct inode *inode, struct file *filp)
 
 	SCSC_TAG_INFO(MX_MMAP, "open %p\n", filp);
 
+	if (test_and_set_bit_lock(0, &mx_dev->lock)) {
+		SCSC_TAG_ERR(MX_MMAP, "already open %p\n", filp);
+		return -EBUSY;
+	}
+
 	filp->private_data = mx_dev;
 	mx_dev->filp = filp;
 	ret = kfifo_alloc(&mx_dev->fifo, GDB_TRANSPORT_BUF_LENGTH, GFP_KERNEL);
@@ -276,6 +284,8 @@ int mx_gdb_release(struct inode *inode, struct file *filp)
 		return -EIO;
 	}
 
+	clear_bit_unlock(0, &mx_dev->lock);
+
 	filp->private_data = NULL;
 	mx_dev->filp = NULL;
 	kfifo_free(&mx_dev->fifo);