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Subject[PATCH AUTOSEL for-4.9 27/53] rtc: rx8010: change lock mechanism
Date
From: Fabien Lahoudere <fabien.lahoudere@collabora.co.uk>

[ Upstream commit 666b5d1e9f8762300a410f9548b6e370d71dd382 ]

Remove spinlock and use the "rtc->ops_lock" from RTC subsystem instead.
spin_lock_irqsave() is not needed here because we do not have hard IRQs.

This patch fixes the following issue:

root@GE004097290448 b850v3:~# hwclock --systohc
root@GE004097290448 b850v3:~# hwclock --systohc
root@GE004097290448 b850v3:~# hwclock --systohc
root@GE004097290448 b850v3:~# hwclock --systohc
root@GE004097290448 b850v3:~# hwclock --systohc
[ 82.108175] BUG: spinlock wrong CPU on CPU#0, hwclock/855
[ 82.113660] lock: 0xedb4899c, .magic: dead4ead, .owner: hwclock/855, .owner_cpu: 1
[ 82.121329] CPU: 0 PID: 855 Comm: hwclock Not tainted 4.8.0-00042-g09d5410-dirty #20
[ 82.129078] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
[ 82.135609] Backtrace:
[ 82.138090] [<8010d378>] (dump_backtrace) from [<8010d5c0>] (show_stack+0x20/0x24)
[ 82.145664] r7:ec936000 r6:600a0013 r5:00000000 r4:81031680
[ 82.151402] [<8010d5a0>] (show_stack) from [<80401518>] (dump_stack+0xb4/0xe8)
[ 82.158636] [<80401464>] (dump_stack) from [<8017b8b0>] (spin_dump+0x84/0xcc)
[ 82.165775] r10:00000000 r9:ec936000 r8:81056090 r7:600a0013 r6:edb4899c r5:edb4899c
[ 82.173691] r4:e5033e00 r3:00000000
[ 82.177308] [<8017b82c>] (spin_dump) from [<8017bcb0>] (do_raw_spin_unlock+0x108/0x130)
[ 82.185314] r5:edb4899c r4:edb4899c
[ 82.188938] [<8017bba8>] (do_raw_spin_unlock) from [<8094b93c>] (_raw_spin_unlock_irqrestore+0x34/0x54)
[ 82.198333] r5:edb4899c r4:600a0013
[ 82.201953] [<8094b908>] (_raw_spin_unlock_irqrestore) from [<8065b090>] (rx8010_set_time+0x14c/0x188)
[ 82.211261] r5:00000020 r4:edb48990
[ 82.214882] [<8065af44>] (rx8010_set_time) from [<80653fe4>] (rtc_set_time+0x70/0x104)
[ 82.222801] r7:00000051 r6:edb39da0 r5:edb39c00 r4:ec937e8c
[ 82.228535] [<80653f74>] (rtc_set_time) from [<80655774>] (rtc_dev_ioctl+0x3c4/0x674)
[ 82.236368] r7:00000051 r6:7ecf1b74 r5:00000000 r4:edb39c00
[ 82.242106] [<806553b0>] (rtc_dev_ioctl) from [<80284034>] (do_vfs_ioctl+0xa4/0xa6c)
[ 82.249851] r8:00000003 r7:80284a40 r6:ed1e9c80 r5:edb44e60 r4:7ecf1b74
[ 82.256642] [<80283f90>] (do_vfs_ioctl) from [<80284a40>] (SyS_ioctl+0x44/0x6c)
[ 82.263953] r10:00000000 r9:ec936000 r8:7ecf1b74 r7:4024700a r6:ed1e9c80 r5:00000003
[ 82.271869] r4:ed1e9c80
[ 82.274432] [<802849fc>] (SyS_ioctl) from [<80108520>] (ret_fast_syscall+0x0/0x1c)
[ 82.282005] r9:ec936000 r8:801086c4 r7:00000036 r6:00000000 r5:00000003 r4:0008e1bc
root@GE004097290448 b850v3:~#
Message from syslogd@GE004097290448 at Dec 3 11:17:08 ...
kernel:[ 82.108175] BUG: spinlock wrong CPU on CPU#0, hwclock/855

Message from syslogd@GE004097290448 at Dec 3 11:17:08 ...
kernel:[ 82.113660] lock: 0xedb4899c, .magic: dead4ead, .owner: hwclock/855, .owner_cpu: 1
hwclock --systohc
root@GE004097290448 b850v3:~#

Signed-off-by: Fabien Lahoudere <fabien.lahoudere@collabora.co.uk>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
---
drivers/rtc/rtc-rx8010.c | 24 +++---------------------
1 file changed, 3 insertions(+), 21 deletions(-)

diff --git a/drivers/rtc/rtc-rx8010.c b/drivers/rtc/rtc-rx8010.c
index 7163b91bb773..d08da371912c 100644
--- a/drivers/rtc/rtc-rx8010.c
+++ b/drivers/rtc/rtc-rx8010.c
@@ -63,7 +63,6 @@ struct rx8010_data {
struct i2c_client *client;
struct rtc_device *rtc;
u8 ctrlreg;
- spinlock_t flags_lock;
};

static irqreturn_t rx8010_irq_1_handler(int irq, void *dev_id)
@@ -72,12 +71,12 @@ static irqreturn_t rx8010_irq_1_handler(int irq, void *dev_id)
struct rx8010_data *rx8010 = i2c_get_clientdata(client);
int flagreg;

- spin_lock(&rx8010->flags_lock);
+ mutex_lock(&rx8010->rtc->ops_lock);

flagreg = i2c_smbus_read_byte_data(client, RX8010_FLAG);

if (flagreg <= 0) {
- spin_unlock(&rx8010->flags_lock);
+ mutex_unlock(&rx8010->rtc->ops_lock);
return IRQ_NONE;
}

@@ -101,7 +100,7 @@ static irqreturn_t rx8010_irq_1_handler(int irq, void *dev_id)

i2c_smbus_write_byte_data(client, RX8010_FLAG, flagreg);

- spin_unlock(&rx8010->flags_lock);
+ mutex_unlock(&rx8010->rtc->ops_lock);
return IRQ_HANDLED;
}

@@ -143,7 +142,6 @@ static int rx8010_set_time(struct device *dev, struct rtc_time *dt)
u8 date[7];
int ctrl, flagreg;
int ret;
- unsigned long irqflags;

if ((dt->tm_year < 100) || (dt->tm_year > 199))
return -EINVAL;
@@ -181,11 +179,8 @@ static int rx8010_set_time(struct device *dev, struct rtc_time *dt)
if (ret < 0)
return ret;

- spin_lock_irqsave(&rx8010->flags_lock, irqflags);
-
flagreg = i2c_smbus_read_byte_data(rx8010->client, RX8010_FLAG);
if (flagreg < 0) {
- spin_unlock_irqrestore(&rx8010->flags_lock, irqflags);
return flagreg;
}

@@ -193,8 +188,6 @@ static int rx8010_set_time(struct device *dev, struct rtc_time *dt)
ret = i2c_smbus_write_byte_data(rx8010->client, RX8010_FLAG,
flagreg & ~RX8010_FLAG_VLF);

- spin_unlock_irqrestore(&rx8010->flags_lock, irqflags);
-
return 0;
}

@@ -288,12 +281,9 @@ static int rx8010_set_alarm(struct device *dev, struct rtc_wkalrm *t)
u8 alarmvals[3];
int extreg, flagreg;
int err;
- unsigned long irqflags;

- spin_lock_irqsave(&rx8010->flags_lock, irqflags);
flagreg = i2c_smbus_read_byte_data(client, RX8010_FLAG);
if (flagreg < 0) {
- spin_unlock_irqrestore(&rx8010->flags_lock, irqflags);
return flagreg;
}

@@ -302,14 +292,12 @@ static int rx8010_set_alarm(struct device *dev, struct rtc_wkalrm *t)
err = i2c_smbus_write_byte_data(rx8010->client, RX8010_CTRL,
rx8010->ctrlreg);
if (err < 0) {
- spin_unlock_irqrestore(&rx8010->flags_lock, irqflags);
return err;
}
}

flagreg &= ~RX8010_FLAG_AF;
err = i2c_smbus_write_byte_data(rx8010->client, RX8010_FLAG, flagreg);
- spin_unlock_irqrestore(&rx8010->flags_lock, irqflags);
if (err < 0)
return err;

@@ -404,7 +392,6 @@ static int rx8010_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
struct rx8010_data *rx8010 = dev_get_drvdata(dev);
int ret, tmp;
int flagreg;
- unsigned long irqflags;

switch (cmd) {
case RTC_VL_READ:
@@ -419,16 +406,13 @@ static int rx8010_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
return 0;

case RTC_VL_CLR:
- spin_lock_irqsave(&rx8010->flags_lock, irqflags);
flagreg = i2c_smbus_read_byte_data(rx8010->client, RX8010_FLAG);
if (flagreg < 0) {
- spin_unlock_irqrestore(&rx8010->flags_lock, irqflags);
return flagreg;
}

flagreg &= ~RX8010_FLAG_VLF;
ret = i2c_smbus_write_byte_data(client, RX8010_FLAG, flagreg);
- spin_unlock_irqrestore(&rx8010->flags_lock, irqflags);
if (ret < 0)
return ret;

@@ -466,8 +450,6 @@ static int rx8010_probe(struct i2c_client *client,
rx8010->client = client;
i2c_set_clientdata(client, rx8010);

- spin_lock_init(&rx8010->flags_lock);
-
err = rx8010_init_client(client);
if (err)
return err;
--
2.11.0
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