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Commit 67dfd3a6 authored by Padmanabhan Komanduru's avatar Padmanabhan Komanduru
Browse files

msm: mdss: handle synchronization issues during DSI debugfs read/write 



Handle race condition during read/write operations to DSI debugfs nodes
related to DSI panel ON/OFF commands.

Change-Id: I29c4ad74bf21d4cb5362565e902a682fe7263147
Signed-off-by: default avatarPadmanabhan Komanduru <pkomandu@codeaurora.org>
parent cf32be90

drivers/video/msm/mdss/mdss_dsi.c

+19 −2
Original line number Diff line number Diff line 
/* Copyright (c) 2012-2016, The Linux Foundation. All rights reserved.

/* Copyright (c) 2012-2017, The Linux Foundation. All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 and
@@ -625,6 +625,7 @@ struct buf_data { 
	char *string_buf; /* cmd buf as string, 3 bytes per number */

	int sblen; /* string buffer length */

	int sync_flag;

	struct mutex dbg_mutex; /* mutex to synchronize read/write/flush */

};



struct mdss_dsi_debugfs_info {
@@ -714,6 +715,7 @@ static ssize_t mdss_dsi_cmd_read(struct file *file, char __user *buf, 
	char *bp;

	ssize_t ret = 0;



	mutex_lock(&pcmds->dbg_mutex);

	if (*ppos == 0) {

		kfree(pcmds->string_buf);

		pcmds->string_buf = NULL;
@@ -732,6 +734,7 @@ static ssize_t mdss_dsi_cmd_read(struct file *file, char __user *buf, 
		buffer = kmalloc(bsize, GFP_KERNEL);

		if (!buffer) {

			pr_err("%s: Failed to allocate memory\n", __func__);

			mutex_unlock(&pcmds->dbg_mutex);

			return -ENOMEM;

		}
@@ -767,10 +770,12 @@ static ssize_t mdss_dsi_cmd_read(struct file *file, char __user *buf, 
		kfree(pcmds->string_buf);

		pcmds->string_buf = NULL;

		pcmds->sblen = 0;

		mutex_unlock(&pcmds->dbg_mutex);

		return 0; /* the end */

	}

	ret = simple_read_from_buffer(buf, count, ppos, pcmds->string_buf,

				      pcmds->sblen);

	mutex_unlock(&pcmds->dbg_mutex);

	return ret;

}
@@ -782,6 +787,7 @@ static ssize_t mdss_dsi_cmd_write(struct file *file, const char __user *p, 
	int blen = 0;

	char *string_buf;



	mutex_lock(&pcmds->dbg_mutex);

	if (*ppos == 0) {

		kfree(pcmds->string_buf);

		pcmds->string_buf = NULL;
@@ -793,6 +799,7 @@ static ssize_t mdss_dsi_cmd_write(struct file *file, const char __user *p, 
	string_buf = krealloc(pcmds->string_buf, blen + 1, GFP_KERNEL);

	if (!string_buf) {

		pr_err("%s: Failed to allocate memory\n", __func__);

		mutex_unlock(&pcmds->dbg_mutex);

		return -ENOMEM;

	}
@@ -802,6 +809,7 @@ static ssize_t mdss_dsi_cmd_write(struct file *file, const char __user *p, 
	string_buf[blen] = '\0';

	pcmds->string_buf = string_buf;

	pcmds->sblen = blen;

	mutex_unlock(&pcmds->dbg_mutex);

	return ret;

}
@@ -812,8 +820,12 @@ static int mdss_dsi_cmd_flush(struct file *file, fl_owner_t id) 
	char *buf, *bufp, *bp;

	struct dsi_ctrl_hdr *dchdr;



	if (!pcmds->string_buf)

	mutex_lock(&pcmds->dbg_mutex);



	if (!pcmds->string_buf) {

		mutex_unlock(&pcmds->dbg_mutex);

		return 0;

	}



	/*

	 * Allocate memory for command buffer
@@ -826,6 +838,7 @@ static int mdss_dsi_cmd_flush(struct file *file, fl_owner_t id) 
		kfree(pcmds->string_buf);

		pcmds->string_buf = NULL;

		pcmds->sblen = 0;

		mutex_unlock(&pcmds->dbg_mutex);

		return -ENOMEM;

	}
@@ -850,6 +863,7 @@ static int mdss_dsi_cmd_flush(struct file *file, fl_owner_t id) 
			pr_err("%s: dtsi cmd=%x error, len=%d\n",

				__func__, dchdr->dtype, dchdr->dlen);

			kfree(buf);

			mutex_unlock(&pcmds->dbg_mutex);

			return -EINVAL;

		}

		bp += sizeof(*dchdr);
@@ -861,6 +875,7 @@ static int mdss_dsi_cmd_flush(struct file *file, fl_owner_t id) 
		pr_err("%s: dcs_cmd=%x len=%d error!\n", __func__,

				bp[0], len);

		kfree(buf);

		mutex_unlock(&pcmds->dbg_mutex);

		return -EINVAL;

	}
@@ -873,6 +888,7 @@ static int mdss_dsi_cmd_flush(struct file *file, fl_owner_t id) 
		pcmds->buf = buf;

		pcmds->blen = blen;

	}

	mutex_unlock(&pcmds->dbg_mutex);

	return 0;

}
@@ -887,6 +903,7 @@ struct dentry *dsi_debugfs_create_dcs_cmd(const char *name, umode_t mode, 
				struct dentry *parent, struct buf_data *cmd,

				struct dsi_panel_cmds ctrl_cmds)

{

	mutex_init(&cmd->dbg_mutex);

	cmd->buf = ctrl_cmds.buf;

	cmd->blen = ctrl_cmds.blen;

	cmd->string_buf = NULL;