[PATCH 1/1] mmc: sdhci: fix lockdep error on tunning routine

[b29396@freescale.com (Dong Aisheng)]

The sdhci_execute_tuning routine gets lock separately by
disable_irq(host->irq);
spin_lock(&host->lock);
It will cause the following lockdep error message since the &host->lock
could also be got in irq context.
Use spin_lock_irqsave/spin_unlock_restore instead to get rid of
this error message.

[ INFO: inconsistent lock state ]
3.13.0-rc1+ #287 Not tainted
---------------------------------
inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.
kworker/u2:1/33 [HC0[0]:SC0[0]:HE1:SE1] takes:
 (&(&host->lock)->rlock){?.-...}, at: [<8045f7f4>] sdhci_execute_tuning+0x4c/0x710
{IN-HARDIRQ-W} state was registered at:
  [<8005f030>] mark_lock+0x140/0x6ac
  [<80060760>] __lock_acquire+0xb30/0x1cbc
  [<800620d0>] lock_acquire+0x70/0x84
  [<8061d1c8>] _raw_spin_lock+0x30/0x40
  [<804605cc>] sdhci_irq+0x24/0xa68
  [<8006b1d4>] handle_irq_event_percpu+0x54/0x18c
  [<8006b350>] handle_irq_event+0x44/0x64
  [<8006e50c>] handle_fasteoi_irq+0xa0/0x170
  [<8006a8f0>] generic_handle_irq+0x30/0x44
  [<8000f238>] handle_IRQ+0x54/0xbc
  [<8000864c>] gic_handle_irq+0x30/0x64
  [<80013024>] __irq_svc+0x44/0x5c
  [<80329bf4>] dev_vprintk_emit+0x50/0x58
  [<80329c24>] dev_printk_emit+0x28/0x30
  [<80329fec>] __dev_printk+0x4c/0x90
  [<8032a180>] dev_err+0x3c/0x48
  [<802dd4f0>] _regulator_get+0x158/0x1cc
  [<802dd5b4>] regulator_get_optional+0x18/0x1c
  [<80461df4>] sdhci_add_host+0x42c/0xbd8
  [<80464820>] sdhci_esdhc_imx_probe+0x378/0x67c
  [<8032ee88>] platform_drv_probe+0x20/0x50
  [<8032d48c>] driver_probe_device+0x118/0x234
  [<8032d690>] __driver_attach+0x9c/0xa0
  [<8032b89c>] bus_for_each_dev+0x68/0x9c
  [<8032cf44>] driver_attach+0x20/0x28
  [<8032cbc8>] bus_add_driver+0x148/0x1f4
  [<8032dce0>] driver_register+0x80/0x100
  [<8032ee54>] __platform_driver_register+0x50/0x64
  [<8084b094>] sdhci_esdhc_imx_driver_init+0x18/0x20
  [<80008980>] do_one_initcall+0x108/0x16c
  [<8081cca4>] kernel_init_freeable+0x10c/0x1d0
  [<80611b28>] kernel_init+0x10/0x120
  [<8000e9c8>] ret_from_fork+0x14/0x2c
irq event stamp: 805
hardirqs last  enabled at (805): [<8061d43c>] _raw_spin_unlock_irqrestore+0x38/0x4c
hardirqs last disabled at (804): [<8061d2c8>] _raw_spin_lock_irqsave+0x24/0x54
softirqs last  enabled at (570): [<8002b824>] __do_softirq+0x1c4/0x290
softirqs last disabled at (561): [<8002bcf4>] irq_exit+0xb4/0x10c

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&(&host->lock)->rlock);
  <Interrupt>
    lock(&(&host->lock)->rlock);

 *** DEADLOCK ***

2 locks held by kworker/u2:1/33:
 #0:  (kmmcd){.+.+..}, at: [<8003db18>] process_one_work+0x128/0x468
 #1:  ((&(&host->detect)->work)){+.+...}, at: [<8003db18>] process_one_work+0x128/0x468

stack backtrace:
CPU: 0 PID: 33 Comm: kworker/u2:1 Not tainted 3.13.0-rc1+ #287
Workqueue: kmmcd mmc_rescan
Backtrace:
[<80012160>] (dump_backtrace+0x0/0x10c) from [<80012438>] (show_stack+0x18/0x1c)
 r6:bfad0900 r5:00000000 r4:8088ecc8 r3:bfad0900
[<80012420>] (show_stack+0x0/0x1c) from [<806169ec>] (dump_stack+0x84/0x9c)
[<80616968>] (dump_stack+0x0/0x9c) from [<806147b4>] (print_usage_bug+0x260/0x2d0)
 r5:8076ba88 r4:80977410
[<80614554>] (print_usage_bug+0x0/0x2d0) from [<8005f0d0>] (mark_lock+0x1e0/0x6ac)
 r9:8005e678 r8:00000000 r7:bfad0900 r6:00001015 r5:bfad0cd0
r4:00000002
[<8005eef0>] (mark_lock+0x0/0x6ac) from [<80060234>] (__lock_acquire+0x604/0x1cbc)
[<8005fc30>] (__lock_acquire+0x0/0x1cbc) from [<800620d0>] (lock_acquire+0x70/0x84)
[<80062060>] (lock_acquire+0x0/0x84) from [<8061d1c8>] (_raw_spin_lock+0x30/0x40)
 r7:00000000 r6:bfb63000 r5:00000000 r4:bfb60568
[<8061d198>] (_raw_spin_lock+0x0/0x40) from [<8045f7f4>] (sdhci_execute_tuning+0x4c/0x710)
 r4:bfb60000
[<8045f7a8>] (sdhci_execute_tuning+0x0/0x710) from [<80453454>] (mmc_sd_init_card+0x5f8/0x660)
[<80452e5c>] (mmc_sd_init_card+0x0/0x660) from [<80453748>] (mmc_attach_sd+0xb4/0x180)
 r9:bf92d400 r8:8065f364 r7:00061a80 r6:bfb60000 r5:8065f358
r4:bfb60000
[<80453694>] (mmc_attach_sd+0x0/0x180) from [<8044d9f8>] (mmc_rescan+0x284/0x2f0)
 r5:8065f358 r4:bfb602f8
[<8044d774>] (mmc_rescan+0x0/0x2f0) from [<8003db94>] (process_one_work+0x1a4/0x468)
 r8:00000000 r7:bfb55eb0 r6:bf80dc00 r5:bfb602f8 r4:bfb35980
r3:8044d774
[<8003d9f0>] (process_one_work+0x0/0x468) from [<8003e850>] (worker_thread+0x118/0x3e0)
[<8003e738>] (worker_thread+0x0/0x3e0) from [<80044de0>] (kthread+0xd4/0xf0)
[<80044d0c>] (kthread+0x0/0xf0) from [<8000e9c8>] (ret_from_fork+0x14/0x2c)
 r7:00000000 r6:00000000 r5:80044d0c r4:bfb37b40

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Chris Ball <cjb@laptop.org>
Cc: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Dong Aisheng <b29396@freescale.com>

---
It's strange that this issue did not happen on kernel 3.10.17 with the same
code. And looking at the code, before call spin_lock we already disable the mmc
controller irq, per on my understanding, the deadlock given by lockdep may not
be able to happen(pls fix me if wrong).
May the lockdep not track the specific irq disable?
Copy lockdep guy to comment.
---
 drivers/mmc/host/sdhci.c |   20 +++++++-------------
 1 files changed, 7 insertions(+), 13 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index a104bb1..c5d5f53 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1876,12 +1876,12 @@ static int sdhci_execute_tuning(struct mmc_host *mmc, u32 opcode)
 	unsigned long timeout;
 	int err = 0;
 	bool requires_tuning_nonuhs = false;
+	unsigned long flags;
 
 	host = mmc_priv(mmc);
 
 	sdhci_runtime_pm_get(host);
-	disable_irq(host->irq);
-	spin_lock(&host->lock);
+	spin_lock_irqsave(&host->lock, flags);
 
 	ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
 
@@ -1901,15 +1901,13 @@ static int sdhci_execute_tuning(struct mmc_host *mmc, u32 opcode)
 	    requires_tuning_nonuhs)
 		ctrl |= SDHCI_CTRL_EXEC_TUNING;
 	else {
-		spin_unlock(&host->lock);
-		enable_irq(host->irq);
+		spin_unlock_irqrestore(&host->lock, flags);
 		sdhci_runtime_pm_put(host);
 		return 0;
 	}
 
 	if (host->ops->platform_execute_tuning) {
-		spin_unlock(&host->lock);
-		enable_irq(host->irq);
+		spin_unlock_irqrestore(&host->lock, flags);
 		err = host->ops->platform_execute_tuning(host, opcode);
 		sdhci_runtime_pm_put(host);
 		return err;
@@ -1982,15 +1980,12 @@ static int sdhci_execute_tuning(struct mmc_host *mmc, u32 opcode)
 		host->cmd = NULL;
 		host->mrq = NULL;
 
-		spin_unlock(&host->lock);
-		enable_irq(host->irq);
-
+		spin_unlock_irqrestore(&host->lock, flags);
 		/* Wait for Buffer Read Ready interrupt */
 		wait_event_interruptible_timeout(host->buf_ready_int,
 					(host->tuning_done == 1),
 					msecs_to_jiffies(50));
-		disable_irq(host->irq);
-		spin_lock(&host->lock);
+		spin_lock_irqsave(&host->lock, flags);
 
 		if (!host->tuning_done) {
 			pr_info(DRIVER_NAME ": Timeout waiting for "
@@ -2065,8 +2060,7 @@ out:
 		err = 0;
 
 	sdhci_clear_set_irqs(host, SDHCI_INT_DATA_AVAIL, ier);
-	spin_unlock(&host->lock);
-	enable_irq(host->irq);
+	spin_unlock_irqrestore(&host->lock, flags);
 	sdhci_runtime_pm_put(host);
 
 	return err;
-- 
1.7.2.rc3