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Commit 719767d5 authored by Sarangdhar Joshi's avatar Sarangdhar Joshi
Browse files

coresight: add spinlock across stm channel allocation 



There appears to be a race condition during stm channel allocation where
two processes running in parallel get same channel. Fix this by adding a
spinlock across channel allocation logic until we figure out a root cause
of this issue.

Change-Id: Ifcc655957adae3c58d8b329d8cd5c0551a26d5c6
Signed-off-by: default avatarSarangdhar Joshi <spjoshi@codeaurora.org>
parent 763e35c9

drivers/coresight/coresight-stm.c

+33 −17
Original line number Diff line number Diff line 
/* Copyright (c) 2012-2013, The Linux Foundation. All rights reserved.

/* Copyright (c) 2012-2014, 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
@@ -148,12 +148,13 @@ static struct stm_drvdata *stmdrvdata; 
static int stm_hwevent_isenable(struct stm_drvdata *drvdata)

{

	int ret = 0;

	unsigned long flags;



	spin_lock(&drvdata->spinlock);

	spin_lock_irqsave(&drvdata->spinlock, flags);

	if (drvdata->enable)

		if (BVAL(stm_readl(drvdata, STMHEMCR), 0))

			ret = stm_readl(drvdata, STMHEER) == 0 ? 0 : 1;

	spin_unlock(&drvdata->spinlock);

	spin_unlock_irqrestore(&drvdata->spinlock, flags);



	return ret;

}
@@ -175,13 +176,14 @@ static void __stm_hwevent_enable(struct stm_drvdata *drvdata) 
static int stm_hwevent_enable(struct stm_drvdata *drvdata)

{

	int ret = 0;

	unsigned long flags;



	spin_lock(&drvdata->spinlock);

	spin_lock_irqsave(&drvdata->spinlock, flags);

	if (drvdata->enable)

		__stm_hwevent_enable(drvdata);

	else

		ret = -EINVAL;

	spin_unlock(&drvdata->spinlock);

	spin_unlock_irqrestore(&drvdata->spinlock, flags);



	return ret;

}
@@ -189,11 +191,12 @@ static int stm_hwevent_enable(struct stm_drvdata *drvdata) 
static int stm_port_isenable(struct stm_drvdata *drvdata)

{

	int ret = 0;

	unsigned long flags;



	spin_lock(&drvdata->spinlock);

	spin_lock_irqsave(&drvdata->spinlock, flags);

	if (drvdata->enable)

		ret = stm_readl(drvdata, STMSPER) == 0 ? 0 : 1;

	spin_unlock(&drvdata->spinlock);

	spin_unlock_irqrestore(&drvdata->spinlock, flags);



	return ret;

}
@@ -211,13 +214,14 @@ static void __stm_port_enable(struct stm_drvdata *drvdata) 
static int stm_port_enable(struct stm_drvdata *drvdata)

{

	int ret = 0;

	unsigned long flags;



	spin_lock(&drvdata->spinlock);

	spin_lock_irqsave(&drvdata->spinlock, flags);

	if (drvdata->enable)

		__stm_port_enable(drvdata);

	else

		ret = -EINVAL;

	spin_unlock(&drvdata->spinlock);

	spin_unlock_irqrestore(&drvdata->spinlock, flags);



	return ret;

}
@@ -240,15 +244,16 @@ static int stm_enable(struct coresight_device *csdev) 
{

	struct stm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);

	int ret;

	unsigned long flags;



	ret = clk_prepare_enable(drvdata->clk);

	if (ret)

		return ret;



	spin_lock(&drvdata->spinlock);

	spin_lock_irqsave(&drvdata->spinlock, flags);

	__stm_enable(drvdata);

	drvdata->enable = true;

	spin_unlock(&drvdata->spinlock);

	spin_unlock_irqrestore(&drvdata->spinlock, flags);



	dev_info(drvdata->dev, "STM tracing enabled\n");

	return 0;
@@ -267,10 +272,12 @@ static void __stm_hwevent_disable(struct stm_drvdata *drvdata) 


static void stm_hwevent_disable(struct stm_drvdata *drvdata)

{

	spin_lock(&drvdata->spinlock);

	unsigned long flags;



	spin_lock_irqsave(&drvdata->spinlock, flags);

	if (drvdata->enable)

		__stm_hwevent_disable(drvdata);

	spin_unlock(&drvdata->spinlock);

	spin_unlock_irqrestore(&drvdata->spinlock, flags);

}



static void __stm_port_disable(struct stm_drvdata *drvdata)
@@ -285,10 +292,12 @@ static void __stm_port_disable(struct stm_drvdata *drvdata) 


static void stm_port_disable(struct stm_drvdata *drvdata)

{

	spin_lock(&drvdata->spinlock);

	unsigned long flags;



	spin_lock_irqsave(&drvdata->spinlock, flags);

	if (drvdata->enable)

		__stm_port_disable(drvdata);

	spin_unlock(&drvdata->spinlock);

	spin_unlock_irqrestore(&drvdata->spinlock, flags);

}



static void __stm_disable(struct stm_drvdata *drvdata)
@@ -306,11 +315,12 @@ static void __stm_disable(struct stm_drvdata *drvdata) 
static void stm_disable(struct coresight_device *csdev)

{

	struct stm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);

	unsigned long flags;



	spin_lock(&drvdata->spinlock);

	spin_lock_irqsave(&drvdata->spinlock, flags);

	__stm_disable(drvdata);

	drvdata->enable = false;

	spin_unlock(&drvdata->spinlock);

	spin_unlock_irqrestore(&drvdata->spinlock, flags);



	/* Wait for 100ms so that pending data has been written to HW */

	msleep(100);
@@ -333,12 +343,15 @@ static uint32_t stm_channel_alloc(uint32_t off) 
{

	struct stm_drvdata *drvdata = stmdrvdata;

	uint32_t ch;

	unsigned long flags;



	spin_lock_irqsave(&drvdata->spinlock, flags);

	do {

		ch = find_next_zero_bit(drvdata->chs.bitmap,

					NR_STM_CHANNEL, off);

	} while ((ch < NR_STM_CHANNEL) &&

		 test_and_set_bit(ch, drvdata->chs.bitmap));

	spin_unlock_irqrestore(&drvdata->spinlock, flags);



	return ch;

}
@@ -346,8 +359,11 @@ static uint32_t stm_channel_alloc(uint32_t off) 
static void stm_channel_free(uint32_t ch)

{

	struct stm_drvdata *drvdata = stmdrvdata;

	unsigned long flags;



	spin_lock_irqsave(&drvdata->spinlock, flags);

	clear_bit(ch, drvdata->chs.bitmap);

	spin_unlock_irqrestore(&drvdata->spinlock, flags);

}



static int stm_send_64bit(void *addr, const void *data, uint32_t size)