Revert "mmc: fix a race between card-detect rescan and clock-gate work instances"

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@laptop.org>
Cc: <stable@kernel.org>

2 files changed, 6 insertions, 4 deletions

diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index 2b200c1cfbba..461e6a17fb90 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -94,7 +94,7 @@ static void mmc_host_clk_gate_delayed(struct mmc_host *host)
                 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(struct mmc_host *host)
                 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 *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)
         }
         host->clk_requests++;
         spin_unlock_irqrestore(&host->clk_lock, flags);
-        mmc_release_host(host);
+        mutex_unlock(&host->clk_gate_mutex);
 }
 
 /**
@@ -215,6 +215,7 @@ static inline void mmc_host_clk_init(struct mmc_host *host)
         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);
 }
 
 /**
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index eb792cb6d745..bcb793ec7374 100644
--- 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 */