kernel report one possible dead lock during imx6sx pcie
suspend resume stress tests, after enable Lock Debugging.
platform: imx6sx sdb board + xhci(pcie2usb3.0 ep)
reason: usleep_range used in imx6_pcie_link_up maybe scheduled
out from dw_pcie_valid_config.isra...
About details, please see the following logs.
solution: replace the usleep_range(1000, 2000) by udelay(10) and
enlarge the loop counter.
logs:
[ 50.643062] xhci_hcd 0000:01:00.0: Refused to change power state, currently in D3
[ 50.653390]
[ 50.654898] =========================================================
[ 50.661343] [ INFO: possible irq lock inversion dependency detected ]
[ 50.667792] 3.17.0-rc2-01341-gfc43ff7-dirty #101 Not tainted
[ 50.673454] ---------------------------------------------------------
[ 50.679898] kworker/u2:2/48 just changed the state of lock:
[ 50.685477] (pci_lock){+.....}, at: [<802d650c>] pci_bus_read_config_dword+0x44/0x94
[ 50.693394] but this lock was taken by another, HARDIRQ-safe lock in the past:
[ 50.700619] (&irq_desc_lock_class){-.-...}
and interrupts could create inverse lock ordering between them.
[ 50.710843]
[ 50.710843] other info that might help us debug this:
[ 50.717377] Possible interrupt unsafe locking scenario:
[ 50.717377]
[ 50.724169] CPU0 CPU1
[ 50.728702] ---- ----
[ 50.733234] lock(pci_lock);
[ 50.736232] local_irq_disable();
[ 50.742154] lock(&irq_desc_lock_class);
[ 50.748713] lock(pci_lock);
[ 50.754229] <Interrupt>
[ 50.756852] lock(&irq_desc_lock_class);
[ 50.761065]
[ 50.761065] *** DEADLOCK ***
...
[ 52.119515] [<806e8ad0>] (schedule_hrtimeout_range) from [<80077e90>] (usleep_range+0x50/0x58)
[ 52.128141] [<80077e40>] (usleep_range) from [<802f3694>] (imx6_pcie_link_up+0x48/0x16c)
[ 52.136242] [<802f364c>] (imx6_pcie_link_up) from [<802f1b74>] (dw_pcie_valid_config.isra.10+0x40/0x7c)
[ 52.145637] r6:ae72606d r5:ae72606c r4:ae711228
[ 52.150311] [<802f1b34>] (dw_pcie_valid_config.isra.10) from [<802f1ca8>] (dw_pcie_rd_conf+0x4c/0x154)
[ 52.159620] r7:00000000 r6:00000000 r5:ae711228 r4:ae726000
[ 52.165355] [<802f1c5c>] (dw_pcie_rd_conf) from [<802d6534>] (pci_bus_read_config_dword+0x6c/0x94)
[ 52.174316] r9:adf4e910 r8:809bc51c r7:00000000 r6:60000153 r5:adc3fd5c r4:ae726000
[ 52.182152] [<802d64c8>] (pci_bus_read_config_dword) from [<802db588>] (pci_restore_config_dword+0x54/0xa4)
[ 52.191894] r6:00000024 r5:0000000a r4:ae61e000
[ 52.196570] [<802db534>] (pci_restore_config_dword) from [<802dd150>] (pci_restore_state.part.37+0x7c/0x1f8)
[ 52.206399] r8:802e086c r7:ae61dfe8 r6:519e2024 r5:ae61e000 r4:ae61dffc
[ 52.213187] [<802dd0d4>] (pci_restore_state.part.37) from [<802dd2e8>] (pci_restore_state+0x1c/0x20)
[ 52.222322] r7:adc3fea8 r6:809d90e0 r5:ae61e000 r4:ae61e068
[ 52.228056] [<802dd2cc>] (pci_restore_state) from [<802e0894>] (pci_pm_resume_noirq+0x28/0xa4)
[ 52.236683] [<802e086c>] (pci_pm_resume_noirq) from [<8037ea1c>] (dpm_run_callback.isra.12+0x34/0x7c)
Signed-off-by: Richard Zhu <r65037@xxxxxxxxxxxxx>
---
drivers/pci/host/pci-imx6.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
index c74e87d..4334de6 100644
--- a/drivers/pci/host/pci-imx6.c
+++ b/drivers/pci/host/pci-imx6.c
@@ -519,7 +519,7 @@ static void imx6_pcie_reset_phy(struct pcie_port *pp)
static int imx6_pcie_link_up(struct pcie_port *pp)
{
u32 rc, debug_r0, rx_valid;
- int count = 5;
+ int count = 500;
/*
* Test if the PHY reports that the link is up and also that the LTSSM
@@ -550,7 +550,7 @@ static int imx6_pcie_link_up(struct pcie_port *pp)
* Wait a little bit, then re-check if the link finished
* the training.
*/
- usleep_range(1000, 2000);
+ udelay(10);
}
/*
* From L0, initiate MAC entry to gen2 if EP/RC supports gen2.
--
1.9.1
--
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