linux-kernel - [52/71] Revert "mmc: fix a race between card-detect rescan and clock-gate work instances"

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Message-Id: <20110519180559.278337910@clark.kroah.org>
Date:	Thu, 19 May 2011 11:05:20 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Chris Ball <cjb@...top.org>
Subject: [52/71] Revert "mmc: fix a race between card-detect rescan and clock-gate work instances"

2.6.38-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Chris Ball <cjb@...top.org>

commit 86f315bbb2374f1f077500ad131dd9b71856e697 upstream.

This reverts commit 26fc8775b51484d8c0a671198639c6d5ae60533e, which has
been reported to cause boot/resume-time crashes for some users:

https://bbs.archlinux.org/viewtopic.php?id=118751.

Signed-off-by: Chris Ball <cjb@...top.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/mmc/core/host.c  |    9 +++++----
 include/linux/mmc/host.h |    1 +
 2 files changed, 6 insertions(+), 4 deletions(-)

--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -94,7 +94,7 @@ static void mmc_host_clk_gate_delayed(st
 		spin_unlock_irqrestore(&host->clk_lock, flags);
 		return;
 	}
-	mmc_claim_host(host);
+	mutex_lock(&host->clk_gate_mutex);
 	spin_lock_irqsave(&host->clk_lock, flags);
 	if (!host->clk_requests) {
 		spin_unlock_irqrestore(&host->clk_lock, flags);
@@ -104,7 +104,7 @@ static void mmc_host_clk_gate_delayed(st
 		pr_debug("%s: gated MCI clock\n", mmc_hostname(host));
 	}
 	spin_unlock_irqrestore(&host->clk_lock, flags);
-	mmc_release_host(host);
+	mutex_unlock(&host->clk_gate_mutex);
 }
 
 /*
@@ -130,7 +130,7 @@ void mmc_host_clk_ungate(struct mmc_host
 {
 	unsigned long flags;
 
-	mmc_claim_host(host);
+	mutex_lock(&host->clk_gate_mutex);
 	spin_lock_irqsave(&host->clk_lock, flags);
 	if (host->clk_gated) {
 		spin_unlock_irqrestore(&host->clk_lock, flags);
@@ -140,7 +140,7 @@ void mmc_host_clk_ungate(struct mmc_host
 	}
 	host->clk_requests++;
 	spin_unlock_irqrestore(&host->clk_lock, flags);
-	mmc_release_host(host);
+	mutex_unlock(&host->clk_gate_mutex);
 }
 
 /**
@@ -218,6 +218,7 @@ static inline void mmc_host_clk_init(str
 	host->clk_gated = false;
 	INIT_WORK(&host->clk_gate_work, mmc_host_clk_gate_work);
 	spin_lock_init(&host->clk_lock);
+	mutex_init(&host->clk_gate_mutex);
 }
 
 /**
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -183,6 +183,7 @@ struct mmc_host {
 	struct work_struct	clk_gate_work; /* delayed clock gate */
 	unsigned int		clk_old;	/* old clock value cache */
 	spinlock_t		clk_lock;	/* lock for clk fields */
+	struct mutex		clk_gate_mutex;	/* mutex for clock gating */
 #endif
 
 	/* host specific block data */


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