Re: [PATCH v2 4/4] ARM: OMAP2+: omap_device: fix crash on omap_device removal
From: Grygorii Strashko
Date: Fri Jul 29 2016 - 08:52:56 EST
On 07/29/2016 08:15 AM, Peter Ujfalusi wrote:
On 07/28/16 20:50, Grygorii Strashko wrote:
Below call chain causes system crash when OMAP device is
removed by calling of_platform_depopulate()/device_del():
Should you swap 3 <-> 4 in the series?
Currently patch 3 will introduce the crash you are fixing in patch 4...
No. The key function here is device_del() - of_device_unregister(),
which was used previously has the same issue:
of_device_unregister() -> device_unregister() ->device_del()
In general all these patches are independent and they were created just
in bugs detection order.
device_del()
- blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
BUS_NOTIFY_DEL_DEVICE, dev);
- _omap_device_notifier_call()
- omap_device_delete()
- od->pdev->archdata.od = NULL;
kfree(od->hwmods);
kfree(od);
- bus_remove_device()
- device_release_driver()
- __device_release_driver()
- pm_runtime_get_sync()
- _od_runtime_resume()
- omap_hwmod_enable() <- OOPS od's delted already
Backtrace:
Unable to handle kernel NULL pointer dereference at virtual address 0000000d
pgd = eb100000
[0000000d] *pgd=ad6e1831, *pte=00000000, *ppte=00000000
Internal error: Oops: 17 [#1] PREEMPT SMP ARM
CPU: 1 PID: 1273 Comm: modprobe Not tainted 4.4.15-rt19-00115-ge4d3cd3-dirty #68
Hardware name: Generic DRA74X (Flattened Device Tree)
task: eb1ee800 ti: ec962000 task.ti: ec962000
PC is at omap_device_enable+0x10/0x90
LR is at _od_runtime_resume+0x10/0x24
[...]
[<c00299dc>] (omap_device_enable) from [<c0029a6c>] (_od_runtime_resume+0x10/0x24)
[<c0029a6c>] (_od_runtime_resume) from [<c04ad404>] (__rpm_callback+0x20/0x34)
[<c04ad404>] (__rpm_callback) from [<c04ad438>] (rpm_callback+0x20/0x80)
[<c04ad438>] (rpm_callback) from [<c04aee28>] (rpm_resume+0x48c/0x964)
[<c04aee28>] (rpm_resume) from [<c04af360>] (__pm_runtime_resume+0x60/0x88)
[<c04af360>] (__pm_runtime_resume) from [<c04a4974>] (__device_release_driver+0x30/0x100)
[<c04a4974>] (__device_release_driver) from [<c04a4a60>] (device_release_driver+0x1c/0x28)
[<c04a4a60>] (device_release_driver) from [<c04a38c0>] (bus_remove_device+0xec/0x144)
[<c04a38c0>] (bus_remove_device) from [<c04a0764>] (device_del+0x10c/0x210)
[<c04a0764>] (device_del) from [<c04a67b0>] (platform_device_del+0x18/0x84)
[<c04a67b0>] (platform_device_del) from [<c04a6828>] (platform_device_unregister+0xc/0x20)
[<c04a6828>] (platform_device_unregister) from [<c05adcfc>] (of_platform_device_destroy+0x8c/0x90)
[<c05adcfc>] (of_platform_device_destroy) from [<c04a02f0>] (device_for_each_child+0x4c/0x78)
[<c04a02f0>] (device_for_each_child) from [<c05adc5c>] (of_platform_depopulate+0x30/0x44)
[<c05adc5c>] (of_platform_depopulate) from [<bf123920>] (cpsw_remove+0x68/0xf4 [ti_cpsw])
[<bf123920>] (cpsw_remove [ti_cpsw]) from [<c04a68d8>] (platform_drv_remove+0x24/0x3c)
[<c04a68d8>] (platform_drv_remove) from [<c04a49c8>] (__device_release_driver+0x84/0x100)
[<c04a49c8>] (__device_release_driver) from [<c04a4b20>] (driver_detach+0xac/0xb0)
[<c04a4b20>] (driver_detach) from [<c04a3be8>] (bus_remove_driver+0x60/0xd4)
[<c04a3be8>] (bus_remove_driver) from [<c00d9870>] (SyS_delete_module+0x184/0x20c)
[<c00d9870>] (SyS_delete_module) from [<c0010540>] (ret_fast_syscall+0x0/0x1c)
Code: e3500000 e92d4070 1590630c 01a06000 (e5d6300d)
Hence, fix it by using BUS_NOTIFY_REMOVED_DEVICE event for OMAP device
deletion which is sent when DD has finished processing of device
deletion.
Cc: Tony Lindgren <tony@xxxxxxxxxxx>
Cc: Tero Kristo <t-kristo@xxxxxx>
Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx>
---
arch/arm/mach-omap2/omap_device.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm/mach-omap2/omap_device.c b/arch/arm/mach-omap2/omap_device.c
index f7ff3b9..208f115 100644
--- a/arch/arm/mach-omap2/omap_device.c
+++ b/arch/arm/mach-omap2/omap_device.c
@@ -194,7 +194,7 @@ static int _omap_device_notifier_call(struct notifier_block *nb,
int err;
switch (event) {
- case BUS_NOTIFY_DEL_DEVICE:
+ case BUS_NOTIFY_REMOVED_DEVICE:
if (pdev->archdata.od)
omap_device_delete(pdev->archdata.od);
break;
--
regards,
-grygorii