Re: rtsx_pci_sdmmc lockdep splat

From: micky
Date: Mon Apr 21 2014 - 04:43:41 EST

Hi Borislav

Thank you for test the patch. It seems we can't use tasklet here due to mutex_lock.
And the spinlock may removed, I'm prepare to resend a different patch later.

Best Regards.
micky
On 04/20/2014 08:20 PM, Borislav Petkov wrote:
Hi,

On Wed, Apr 16, 2014 at 09:50:15AM +0800, micky wrote:
From: Micky Ching<micky_ching@xxxxxxxxxxxxxx>

To avoid dead lock, we need make sure host->lock is always acquire
before pcr->lock. But in irq handler, we acquired pcr->lock in rtsx mfd
driver, and sd_isr_done_transfer() is called during pcr->lock already
acquired. Since in sd_isr_done_transfer() the only work we do is schdule
tasklet, the cmd_tasklet and data_tasklet never conflict, so it is safe
to remove spin_lock() here.

Signed-off-by: Micky Ching<micky_ching@xxxxxxxxxxxxxx>
---
drivers/mmc/host/rtsx_pci_sdmmc.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/mmc/host/rtsx_pci_sdmmc.c b/drivers/mmc/host/rtsx_pci_sdmmc.c
index 453e1d4..40695e0 100644
--- a/drivers/mmc/host/rtsx_pci_sdmmc.c
+++ b/drivers/mmc/host/rtsx_pci_sdmmc.c
@@ -108,12 +108,10 @@ static void sd_isr_done_transfer(struct platform_device *pdev)
{
struct realtek_pci_sdmmc *host = platform_get_drvdata(pdev);
- spin_lock(&host->lock);
if (host->cmd)
tasklet_schedule(&host->cmd_tasklet);
- if (host->data)
+ else if (host->data)
tasklet_schedule(&host->data_tasklet);
- spin_unlock(&host->lock);
}
static void sd_request_timeout(unsigned long host_addr)
--
Patch wouldn't apply against rc1, so I had to add it by hand, diff
below.

---
diff --git a/drivers/mmc/host/rtsx_pci_sdmmc.c b/drivers/mmc/host/rtsx_pci_sdmmc.c
index 5fb994f9a653..d1d65c0d8d2e 100644
--- a/drivers/mmc/host/rtsx_pci_sdmmc.c
+++ b/drivers/mmc/host/rtsx_pci_sdmmc.c
@@ -109,12 +109,10 @@ static void sd_isr_done_transfer(struct platform_device *pdev)
{
struct realtek_pci_sdmmc *host = platform_get_drvdata(pdev);
- spin_lock(&host->lock);
if (host->cmd)
tasklet_schedule(&host->cmd_tasklet);
- if (host->data)
+ else if (host->data)
tasklet_schedule(&host->data_tasklet);
- spin_unlock(&host->lock);
}
static void sd_request_timeout(unsigned long host_addr)
--

Still needs more love:

[ 95.112797] rtsx_pci_sdmmc rtsx_pci_sdmmc.0: sdmmc_get_cd: RTSX_BIPR = 0x00010000
[ 95.115700] mmc0: mmc_rescan_try_freq: trying to init card at 400000 Hz
[ 95.118040] mmc0: clock 0Hz busmode 2 powermode 1 cs 0 Vdd 21 width 0 timing 0
[ 95.122504] rtsx_pci_sdmmc rtsx_pci_sdmmc.0: sdmmc_switch_voltage: signal_voltage = 0
[ 95.139469] mmc0: clock 400000Hz busmode 2 powermode 2 cs 0 Vdd 21 width 0 timing 0
[ 95.155461] mmc0: starting CMD52 arg 00000c00 flags 00000195
[ 95.158617] rtsx_pci_sdmmc rtsx_pci_sdmmc.0: sd_send_cmd: SD/MMC CMD 52, arg = 0x00000c00
[ 95.255497] rtsx_pci_sdmmc rtsx_pci_sdmmc.0: timeout for request
[ 95.258412] ------------[ cut here ]------------
[ 95.261163] WARNING: CPU: 0 PID: 3 at kernel/locking/mutex.c:698 __mutex_unlock_slowpath+0x124/0x180()
[ 95.264120] DEBUG_LOCKS_WARN_ON(in_interrupt())
[ 95.264222] Modules linked in: cpufreq_stats cpufreq_conservative cpufreq_powersave cpufreq_userspace binfmt_misc uinput ipv6 vfat fat rtsx_pci_sdmmc mmc_core arc4 radeon rtl8192ce snd_hda_codec_conexant snd_hda_codec_generic snd_hda_codec_hdmi snd_hda_intel rtl_pci rtlwifi snd_hda_controller snd_hda_codec mac80211 cfg80211 snd_hwdep snd_pcm drm_kms_helper pcspkr k10temp evdev snd_seq thermal thinkpad_acpi ehci_pci nvram rtsx_pci mfd_core snd_seq_device rtl8192c_common snd_timer ohci_pci ohci_hcd ehci_hcd snd battery ttm ac video button soundcore
[ 95.264231] CPU: 0 PID: 3 Comm: ksoftirqd/0 Not tainted 3.15.0-rc1+ #1
[ 95.264235] Hardware name: LENOVO 30515QG/30515QG, BIOS 8RET30WW (1.12 ) 09/15/2011
[ 95.264246] 0000000000000009 ffff8801198f3c50 ffffffff81522644 ffff8801198f3c98
[ 95.264254] ffff8801198f3c88 ffffffff810701fc ffff8800c0ec1230 ffff8800c28b5c30
[ 95.264262] ffff8800c0ec1000 ffff8800bea267b0 0000000000000000 ffff8801198f3ce8
[ 95.264264] Call Trace:
[ 95.264277] [<ffffffff81522644>] dump_stack+0x4e/0x7a
[ 95.264288] [<ffffffff810701fc>] warn_slowpath_common+0x8c/0xc0
[ 95.264297] [<ffffffff8107027c>] warn_slowpath_fmt+0x4c/0x50
[ 95.264305] [<ffffffff815294c4>] __mutex_unlock_slowpath+0x124/0x180
[ 95.264311] [<ffffffff8152952e>] mutex_unlock+0xe/0x10
[ 95.264324] [<ffffffffa0067119>] sd_finish_request+0xd9/0x1c0 [rtsx_pci_sdmmc]
[ 95.264332] [<ffffffff810751a0>] tasklet_action+0x110/0x170
[ 95.264338] [<ffffffff810756ba>] __do_softirq+0x12a/0x320
[ 95.264345] [<ffffffff810758dd>] run_ksoftirqd+0x2d/0x50
[ 95.264354] [<ffffffff8109be75>] smpboot_thread_fn+0x175/0x2b0
[ 95.264363] [<ffffffff8109bd00>] ? SyS_setgroups+0x150/0x150
[ 95.264372] [<ffffffff8109497c>] kthread+0xfc/0x120
[ 95.264382] [<ffffffff81094880>] ? kthread_create_on_node+0x1f0/0x1f0
[ 95.264390] [<ffffffff8152bfec>] ret_from_fork+0x7c/0xb0
[ 95.264398] [<ffffffff81094880>] ? kthread_create_on_node+0x1f0/0x1f0
[ 95.264403] ---[ end trace e7e46e1611dc934d ]---



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