* Re: [PATCH v5 04/10] PCI: rockchip: fix system hang up if activating CONFIG_DEBUG_SHIRQ
2017-08-24 20:21 ` [PATCH v5 04/10] PCI: rockchip: fix system hang up if activating CONFIG_DEBUG_SHIRQ Bjorn Helgaas
@ 2017-08-24 21:10 ` Dmitry Torokhov
2017-08-25 1:44 ` Brian Norris
2017-08-25 1:05 ` jeffy
2017-08-25 1:38 ` Shawn Lin
2 siblings, 1 reply; 5+ messages in thread
From: Dmitry Torokhov @ 2017-08-24 21:10 UTC (permalink / raw)
To: Bjorn Helgaas
Cc: Shawn Lin, Bjorn Helgaas, Linux PCI,
open list:ARM/Rockchip SoC..., Brian Norris, Jeffy Chen,
Tejun Heo, Michael Turquette, Stephen Boyd, linux-clk
On Thu, Aug 24, 2017 at 1:21 PM, Bjorn Helgaas <helgaas@kernel.org> wrote:
> [+cc Tejun, Dmitry, Michael, Stephen, linux-clk for devm/clk questions]
>
> On Wed, Aug 23, 2017 at 03:02:38PM +0800, Shawn Lin wrote:
>> With CONFIG_DEBUG_SHIRQ enabled, the irq tear down routine
>> would still access the irq handler registed as a shard irq.
>> Per the comment within the function of __free_irq, it says
>> "It's a shared IRQ -- the driver ought to be prepared for
>> an IRQ event to happen even now it's being freed". However
>> when failing to probe the driver, it may disable the clock
>> for accessing the register and the following check for shared
>> irq state would call the irq handler which accesses the register
>> w/o the clk enabled. That will hang the system forever.
>>
>> With adding some dump_stack we could see how that happened.
>>
>> calling rockchip_pcie_driver_init+0x0/0x28 @ 1
>> rockchip-pcie f8000000.pcie: no vpcie3v3 regulator found
>> rockchip-pcie f8000000.pcie: no vpcie1v8 regulator found
>> rockchip-pcie f8000000.pcie: no vpcie0v9 regulator found
>> rockchip-pcie f8000000.pcie: PCIe link training gen1 timeout!
>> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.13.0-rc3-next-20170807-ARCH+ #189
>> Hardware name: Firefly-RK3399 Board (DT)
>> Call trace:
>> [<ffff000008089bf0>] dump_backtrace+0x0/0x250
>> [<ffff000008089eb0>] show_stack+0x20/0x28
>> [<ffff000008c3313c>] dump_stack+0x90/0xb0
>> [<ffff000008632ad4>] rockchip_pcie_read.isra.11+0x54/0x58
>> [<ffff0000086334fc>] rockchip_pcie_client_irq_handler+0x30/0x1a0
>> [<ffff00000813ce98>] __free_irq+0x1c8/0x2dc
>> [<ffff00000813d044>] free_irq+0x44/0x74
>> [<ffff0000081415fc>] devm_irq_release+0x24/0x2c
>> [<ffff00000877429c>] release_nodes+0x1d8/0x30c
>> [<ffff000008774838>] devres_release_all+0x3c/0x5c
>> [<ffff00000876f19c>] driver_probe_device+0x244/0x494
>> [<ffff00000876f50c>] __driver_attach+0x120/0x124
>> [<ffff00000876cb80>] bus_for_each_dev+0x6c/0xac
>> [<ffff00000876e984>] driver_attach+0x2c/0x34
>> [<ffff00000876e3a4>] bus_add_driver+0x244/0x2b0
>> [<ffff000008770264>] driver_register+0x70/0x110
>> [<ffff0000087718b4>] platform_driver_register+0x60/0x6c
>> [<ffff0000091eb108>] rockchip_pcie_driver_init+0x20/0x28
>> [<ffff000008083a2c>] do_one_initcall+0xc8/0x130
>> [<ffff0000091a0ea8>] kernel_init_freeable+0x1a0/0x238
>> [<ffff000008c461cc>] kernel_init+0x18/0x108
>> [<ffff0000080836c0>] ret_from_fork+0x10/0x50
>>
>> In order to fix this, we remove all the clock-disabling from
>> the error handle path and driver's remove function. And replying
>> on the devm_add_action_or_reset to fire the clock-disabling at
>> the appropriate time. Also split out rockchip_pcie_setup_irq
>> and move requesting irq after enabling clks to avoid this kind
>
> Thanks for splitting out the refactoring stuff. That really makes
> this patch much simpler.
>
> IIUC, this really has nothing to do with CONFIG_DEBUG_SHIRQ. It may
> be true that you've only *seen* the problem with CONFIG_DEBUG_SHIRQ
> enabled, but all that config option does is take a situation that
> could happen at any time (another device sharing the IRQ generating an
> interrupt), and force it to happen. So it's just a way to expose an
> existing driver problem.
>
> The real problem is apparently that rockchip_pcie_subsys_irq_handler()
> relies on some clock being enabled, but we're leaving it registered at
> a time when the clock has already been disabled.
>
> You fixed that by using devm_add_action_or_reset() to tell devm to
> disable the clocks *after* releasing the IRQ.
>
> That sort of makes sense, but devm_add_action_or_reset() is a little
> obscure, and this feels like a hole in the devm framework. Seems like
> it would be nice if there were some sort of devm wrapper for
> clk_prepare_enable() so this would happen automatically.
>
> This pattern:
>
> clk = devm_clk_get(...);
> if (IS_ERR(clk)) {
> dev_warn("no clock for ...");
> return PTR_ERR(clk);
> }
>
> ret = clk_prepare_enable(clk);
> if (ret) {
> dev_warn("failed to enable ...");
> return err;
> }
>
> is quite common ("git grep -A10 devm_clk_get | grep clk_prepare_enable
> | wc -l" finds over 400 occurrences). Should there be something to
> simplify this a little?
>
> I also wonder about other PCI host drivers that use both
> clk_prepare_enable() and devm_request_irq(). Maybe Rockchip is
> "special" in that it seems the driver must turn on a clock before it
> can even talk to the host controller, whereas maybe other drivers can
> always talk to the host controller, but need to turn on clocks
> downstream from the controller. I didn't audit them, but I'm
> concerned that some of them might have this same problem.
I proposed devm_clk_prepare_enable() and friends (see
https://lkml.org/lkml/2017/2/14/544), but Stephen did not like it and
mentioned that he and Mike were working on a different solution where
clk_put() would drop all enables. I have not seen any updates on that
though. Maybe we should revisit devm approach?
Thanks.
--
Dmitry
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH v5 04/10] PCI: rockchip: fix system hang up if activating CONFIG_DEBUG_SHIRQ
2017-08-24 21:10 ` Dmitry Torokhov
@ 2017-08-25 1:44 ` Brian Norris
0 siblings, 0 replies; 5+ messages in thread
From: Brian Norris @ 2017-08-25 1:44 UTC (permalink / raw)
To: Dmitry Torokhov
Cc: Bjorn Helgaas, Shawn Lin, Bjorn Helgaas, Linux PCI,
open list:ARM/Rockchip SoC..., Jeffy Chen, Tejun Heo,
Michael Turquette, Stephen Boyd, linux-clk
On Thu, Aug 24, 2017 at 02:10:52PM -0700, Dmitry Torokhov wrote:
> On Thu, Aug 24, 2017 at 1:21 PM, Bjorn Helgaas <helgaas@kernel.org> wrote:
> > [+cc Tejun, Dmitry, Michael, Stephen, linux-clk for devm/clk questions]
> >
> > On Wed, Aug 23, 2017 at 03:02:38PM +0800, Shawn Lin wrote:
> >> With CONFIG_DEBUG_SHIRQ enabled, the irq tear down routine
> >> would still access the irq handler registed as a shard irq.
> >> Per the comment within the function of __free_irq, it says
> >> "It's a shared IRQ -- the driver ought to be prepared for
> >> an IRQ event to happen even now it's being freed". However
> >> when failing to probe the driver, it may disable the clock
> >> for accessing the register and the following check for shared
> >> irq state would call the irq handler which accesses the register
> >> w/o the clk enabled. That will hang the system forever.
Side note: why is this driver even requesting a shared IRQ? This is for
rk3399, and the IRQ is a dedicated GIC interrupt for the PCIe
controller. It shouldn't need to be 'shared'.
The problem still might not be *only* theoretical though, since it's
still possible for this non-shared interrupt to
(a) trigger
(b) concurrently, we remove/tear down (including disable clocks)
(c) we service the IRQ <-- dead, because clock is disabled
(d) if we ever got here... free_irq()
Brian
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v5 04/10] PCI: rockchip: fix system hang up if activating CONFIG_DEBUG_SHIRQ
2017-08-24 20:21 ` [PATCH v5 04/10] PCI: rockchip: fix system hang up if activating CONFIG_DEBUG_SHIRQ Bjorn Helgaas
2017-08-24 21:10 ` Dmitry Torokhov
@ 2017-08-25 1:05 ` jeffy
2017-08-25 1:38 ` Shawn Lin
2 siblings, 0 replies; 5+ messages in thread
From: jeffy @ 2017-08-25 1:05 UTC (permalink / raw)
To: Bjorn Helgaas, Shawn Lin
Cc: Bjorn Helgaas, linux-pci, linux-rockchip, Brian Norris, Tejun Heo,
Dmitry Torokhov, Michael Turquette, Stephen Boyd, linux-clk
Hi Bjorn,
On 08/25/2017 04:21 AM, Bjorn Helgaas wrote:
>> >In order to fix this, we remove all the clock-disabling from
>> >the error handle path and driver's remove function. And replying
>> >on the devm_add_action_or_reset to fire the clock-disabling at
>> >the appropriate time. Also split out rockchip_pcie_setup_irq
>> >and move requesting irq after enabling clks to avoid this kind
> Thanks for splitting out the refactoring stuff. That really makes
> this patch much simpler.
>
> IIUC, this really has nothing to do with CONFIG_DEBUG_SHIRQ. It may
> be true that you've only*seen* the problem with CONFIG_DEBUG_SHIRQ
> enabled, but all that config option does is take a situation that
> could happen at any time (another device sharing the IRQ generating an
> interrupt), and force it to happen. So it's just a way to expose an
> existing driver problem.
yes, and i'm wondering would it make more sense to somehow ignore those
irqs(triggered by other devices, and we don't really need to care since
we already unregistered) than trying to hold all needed resources(clks &
power domains & some other resources maybe) for that?
maybe we can just make sure the irq handler unregistered when we stop
caring about the irqs? or maybe add a flag to tell the irq handler to
stop processing them?
>
> The real problem is apparently that rockchip_pcie_subsys_irq_handler()
> relies on some clock being enabled, but we're leaving it registered at
> a time when the clock has already been disabled.
>
> You fixed that by using devm_add_action_or_reset() to tell devm to
> disable the clocks*after* releasing the IRQ.
>
> That sort of makes sense, but devm_add_action_or_reset() is a little
> obscure, and this feels like a hole in the devm framework. Seems like
> it would be nice if there were some sort of devm wrapper for
> clk_prepare_enable() so this would happen automatically.
>
> This pattern:
>
> clk = devm_clk_get(...);
> if (IS_ERR(clk)) {
> dev_warn("no clock for ...");
> return PTR_ERR(clk);
> }
>
> ret = clk_prepare_enable(clk);
> if (ret) {
> dev_warn("failed to enable ...");
> return err;
> }
>
> is quite common ("git grep -A10 devm_clk_get | grep clk_prepare_enable
> | wc -l" finds over 400 occurrences). Should there be something to
> simplify this a little?
>
> I also wonder about other PCI host drivers that use both
> clk_prepare_enable() and devm_request_irq(). Maybe Rockchip is
> "special" in that it seems the driver must turn on a clock before it
> can even talk to the host controller, whereas maybe other drivers can
> always talk to the host controller, but need to turn on clocks
> downstream from the controller. I didn't audit them, but I'm
> concerned that some of them might have this same problem.
>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH v5 04/10] PCI: rockchip: fix system hang up if activating CONFIG_DEBUG_SHIRQ
2017-08-24 20:21 ` [PATCH v5 04/10] PCI: rockchip: fix system hang up if activating CONFIG_DEBUG_SHIRQ Bjorn Helgaas
2017-08-24 21:10 ` Dmitry Torokhov
2017-08-25 1:05 ` jeffy
@ 2017-08-25 1:38 ` Shawn Lin
2 siblings, 0 replies; 5+ messages in thread
From: Shawn Lin @ 2017-08-25 1:38 UTC (permalink / raw)
To: Bjorn Helgaas
Cc: shawn.lin, Bjorn Helgaas, linux-pci, linux-rockchip, Brian Norris,
Jeffy Chen, Tejun Heo, Dmitry Torokhov, Michael Turquette,
Stephen Boyd, linux-clk
Hi Bjorn,
On在 2017/8/25 4:21, Bjorn Helgaas wrote:
> [+cc Tejun, Dmitry, Michael, Stephen, linux-clk for devm/clk questions]
>
> On Wed, Aug 23, 2017 at 03:02:38PM +0800, Shawn Lin wrote:
>> With CONFIG_DEBUG_SHIRQ enabled, the irq tear down routine
>> would still access the irq handler registed as a shard irq.
>> Per the comment within the function of __free_irq, it says
>> "It's a shared IRQ -- the driver ought to be prepared for
>> an IRQ event to happen even now it's being freed". However
>> when failing to probe the driver, it may disable the clock
>> for accessing the register and the following check for shared
>> irq state would call the irq handler which accesses the register
>> w/o the clk enabled. That will hang the system forever.
>>
>> With adding some dump_stack we could see how that happened.
>>
>> calling rockchip_pcie_driver_init+0x0/0x28 @ 1
>> rockchip-pcie f8000000.pcie: no vpcie3v3 regulator found
>> rockchip-pcie f8000000.pcie: no vpcie1v8 regulator found
>> rockchip-pcie f8000000.pcie: no vpcie0v9 regulator found
>> rockchip-pcie f8000000.pcie: PCIe link training gen1 timeout!
>> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.13.0-rc3-next-20170807-ARCH+ #189
>> Hardware name: Firefly-RK3399 Board (DT)
>> Call trace:
>> [<ffff000008089bf0>] dump_backtrace+0x0/0x250
>> [<ffff000008089eb0>] show_stack+0x20/0x28
>> [<ffff000008c3313c>] dump_stack+0x90/0xb0
>> [<ffff000008632ad4>] rockchip_pcie_read.isra.11+0x54/0x58
>> [<ffff0000086334fc>] rockchip_pcie_client_irq_handler+0x30/0x1a0
>> [<ffff00000813ce98>] __free_irq+0x1c8/0x2dc
>> [<ffff00000813d044>] free_irq+0x44/0x74
>> [<ffff0000081415fc>] devm_irq_release+0x24/0x2c
>> [<ffff00000877429c>] release_nodes+0x1d8/0x30c
>> [<ffff000008774838>] devres_release_all+0x3c/0x5c
>> [<ffff00000876f19c>] driver_probe_device+0x244/0x494
>> [<ffff00000876f50c>] __driver_attach+0x120/0x124
>> [<ffff00000876cb80>] bus_for_each_dev+0x6c/0xac
>> [<ffff00000876e984>] driver_attach+0x2c/0x34
>> [<ffff00000876e3a4>] bus_add_driver+0x244/0x2b0
>> [<ffff000008770264>] driver_register+0x70/0x110
>> [<ffff0000087718b4>] platform_driver_register+0x60/0x6c
>> [<ffff0000091eb108>] rockchip_pcie_driver_init+0x20/0x28
>> [<ffff000008083a2c>] do_one_initcall+0xc8/0x130
>> [<ffff0000091a0ea8>] kernel_init_freeable+0x1a0/0x238
>> [<ffff000008c461cc>] kernel_init+0x18/0x108
>> [<ffff0000080836c0>] ret_from_fork+0x10/0x50
>>
>> In order to fix this, we remove all the clock-disabling from
>> the error handle path and driver's remove function. And replying
>> on the devm_add_action_or_reset to fire the clock-disabling at
>> the appropriate time. Also split out rockchip_pcie_setup_irq
>> and move requesting irq after enabling clks to avoid this kind
>
> Thanks for splitting out the refactoring stuff. That really makes
> this patch much simpler.
>
> IIUC, this really has nothing to do with CONFIG_DEBUG_SHIRQ. It may
> be true that you've only *seen* the problem with CONFIG_DEBUG_SHIRQ
> enabled, but all that config option does is take a situation that
> could happen at any time (another device sharing the IRQ generating an
> interrupt), and force it to happen. So it's just a way to expose an
> existing driver problem.
Right.
>
> The real problem is apparently that rockchip_pcie_subsys_irq_handler()
> relies on some clock being enabled, but we're leaving it registered at
> a time when the clock has already been disabled.
>
> You fixed that by using devm_add_action_or_reset() to tell devm to
> disable the clocks *after* releasing the IRQ.
>
> That sort of makes sense, but devm_add_action_or_reset() is a little
> obscure, and this feels like a hole in the devm framework. Seems like
> it would be nice if there were some sort of devm wrapper for
> clk_prepare_enable() so this would happen automatically.
Yes, I would appreciate it if we have devm wrapper for
clk_prepare_enable so that we don't resort to devm_add_action_or_reset.
>
> This pattern:
>
> clk = devm_clk_get(...);
> if (IS_ERR(clk)) {
> dev_warn("no clock for ...");
> return PTR_ERR(clk);
> }
>
> ret = clk_prepare_enable(clk);
> if (ret) {
> dev_warn("failed to enable ...");
> return err;
> }
>
> is quite common ("git grep -A10 devm_clk_get | grep clk_prepare_enable
> | wc -l" finds over 400 occurrences). Should there be something to
> simplify this a little?
>
> I also wonder about other PCI host drivers that use both
> clk_prepare_enable() and devm_request_irq(). Maybe Rockchip is
> "special" in that it seems the driver must turn on a clock before it
> can even talk to the host controller, whereas maybe other drivers can
IIRC, some of the other ARM SoCs have the same problem.
> always talk to the host controller, but need to turn on clocks
> downstream from the controller. I didn't audit them, but I'm
> concerned that some of them might have this same problem.
So that is my concern as well. But I have to say we may face a worse
situation as I see it by randomly search the DT,
arch/arm64/boot/dts/renesas/r8a7795.dtsi includes a power-domains
for pcie-rcar and pcie-rcar registers shared irq either. So the power-
domain would be powered off once failing to probe or calling ->remove()
immediately even *before* doing devm cleanup. In another word, I don't
have too much confident that renesas's CPU could visit PCIe IP w/o power
domain in 'on' state?
I posted a relevant patch for fixing this for driver core but havn't got
any input from there (https://lkml.org/lkml/2017/8/15/146). That don't
affect pcie-rockchip *now* as we don't have power-domain for that but
it's highly relevant to the problem we are disscussing.
Finally, as a life-saving straw if we don't reach an agreement for
anyone of adding devm clk_prepare_enable wrraper and adjusting the
sequence of powering off power-domain, we have to get rid of using
devm_request_irq and use request_irq/free_irq instead for all
the potential problematic drivers...
>
>> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
>>
>> ---
>>
>> Changes in v5:
>> - rebase on former reconstrtion patches suggested by Bjorn
>>
>> Changes in v4:
>> - split out rockchip_pcie_enable_clocks and reuse
>> rockchip_pcie_enable_clocks and rockchip_pcie_disable_clocks
>> for elsewhere suggested by Jeffy
>>
>> Changes in v3:
>> - check the return value of devm_add_action_or_reset and spilt out
>> rockchip_pcie_setup_irq in order to move requesting irq after
>> enabling clks.
>>
>> Changes in v2:
>> - use devm_add_action_or_reset to fix this ordering suggested by
>> Heiko and Jeffy. Thanks!
>>
>> drivers/pci/host/pcie-rockchip.c | 22 +++++++++++++---------
>> 1 file changed, 13 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/pci/host/pcie-rockchip.c b/drivers/pci/host/pcie-rockchip.c
>> index 971d22b..891b60a 100644
>> --- a/drivers/pci/host/pcie-rockchip.c
>> +++ b/drivers/pci/host/pcie-rockchip.c
>> @@ -1099,10 +1099,6 @@ static int rockchip_pcie_parse_dt(struct rockchip_pcie *rockchip)
>> return PTR_ERR(rockchip->clk_pcie_pm);
>> }
>>
>> - err = rockchip_pcie_setup_irq(rockchip);
>> - if (err)
>> - return err;
>> -
>> rockchip->vpcie12v = devm_regulator_get_optional(dev, "vpcie12v");
>> if (IS_ERR(rockchip->vpcie12v)) {
>> if (PTR_ERR(rockchip->vpcie12v) == -EPROBE_DEFER)
>> @@ -1525,10 +1521,22 @@ static int rockchip_pcie_probe(struct platform_device *pdev)
>> if (err)
>> return err;
>>
>> + err = devm_add_action_or_reset(dev,
>> + rockchip_pcie_disable_clocks,
>> + rockchip);
>> + if (err) {
>> + dev_err(dev, "unable to add action or reset\n");
>> + return err;
>> + }
>> +
>> + err = rockchip_pcie_setup_irq(rockchip);
>> + if (err)
>> + return err;
>> +
>> err = rockchip_pcie_set_vpcie(rockchip);
>> if (err) {
>> dev_err(dev, "failed to set vpcie regulator\n");
>> - goto err_set_vpcie;
>> + return err;
>> }
>>
>> err = rockchip_pcie_init_port(rockchip);
>> @@ -1625,8 +1633,6 @@ static int rockchip_pcie_probe(struct platform_device *pdev)
>> regulator_disable(rockchip->vpcie1v8);
>> if (!IS_ERR(rockchip->vpcie0v9))
>> regulator_disable(rockchip->vpcie0v9);
>> -err_set_vpcie:
>> - rockchip_pcie_disable_clocks(rockchip);
>> return err;
>> }
>>
>> @@ -1648,8 +1654,6 @@ static int rockchip_pcie_remove(struct platform_device *pdev)
>> phy_exit(rockchip->phys[i]);
>> }
>>
>> - rockchip_pcie_disable_clocks(rockchip);
>> -
>> if (!IS_ERR(rockchip->vpcie12v))
>> regulator_disable(rockchip->vpcie12v);
>> if (!IS_ERR(rockchip->vpcie3v3))
>> --
>> 1.9.1
>>
>>
>
>
>
^ permalink raw reply [flat|nested] 5+ messages in thread