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Message-ID: <fc613923-4840-53a2-0831-01a15a6cdf15@caviumnetworks.com>
Date: Fri, 31 Aug 2018 17:50:27 +0530
From: George Cherian <gcherian@...iumnetworks.com>
To: minyard@....org, George Cherian <george.cherian@...ium.com>
Cc: linux-kernel@...r.kernel.org,
openipmi-developer@...ts.sourceforge.net,
Corey Minyard <cminyard@...sta.com>
Subject: Re: [PATCH] ipmi: Fix I2C client removal in the SSIF driver
On 08/31/2018 05:43 PM, Corey Minyard wrote:
>
> On 08/31/2018 06:58 AM, George Cherian wrote:
>>
>>
>> On 08/30/2018 11:44 PM, minyard@....org wrote:
>>>
>>> From: Corey Minyard <cminyard@...sta.com>
>>>
>>> The SSIF driver was removing any client that came in through the
>>> platform interface, but it should only remove clients that it
>>> added. On a failure in the probe function, this could result
>>> in the following oops when the driver is removed and the
>>> client gets unregistered twice:
>>>
>>> CPU: 107 PID: 30266 Comm: rmmod Not tainted 4.18.0+ #80
>>> Hardware name: Cavium Inc. Saber/Saber, BIOS Cavium reference
>>> firmware version 7.0 08/04/2018
>>> pstate: 60400009 (nZCv daif +PAN -UAO)
>>> pc : kernfs_find_ns+0x28/0x120
>>> lr : kernfs_find_and_get_ns+0x40/0x60
>>> sp : ffff00002310fb50
>>> x29: ffff00002310fb50 x28: ffff800a8240f800
>>> x27: 0000000000000000 x26: 0000000000000000
>>> x25: 0000000056000000 x24: ffff000009073000
>>> x23: ffff000008998b38 x22: 0000000000000000
>>> x21: ffff800ed86de820 x20: 0000000000000000
>>> x19: ffff00000913a1d8 x18: 0000000000000000
>>> x17: 0000000000000000 x16: 0000000000000000
>>> x15: 0000000000000000 x14: 5300737265766972
>>> x13: 643d4d4554535953 x12: 0000000000000030
>>> x11: 0000000000000030 x10: 0101010101010101
>>> x9 : ffff800ea06cc3f9 x8 : 0000000000000000
>>> x7 : 0000000000000141 x6 : ffff000009073000
>>> x5 : ffff800adb706b00 x4 : 0000000000000000
>>> x3 : 00000000ffffffff x2 : 0000000000000000
>>> x1 : ffff000008998b38 x0 : ffff000008356760
>>> Process rmmod (pid: 30266, stack limit = 0x00000000e218418d)
>>> Call trace:
>>> kernfs_find_ns+0x28/0x120
>>> kernfs_find_and_get_ns+0x40/0x60
>>> sysfs_unmerge_group+0x2c/0x6c
>>> dpm_sysfs_remove+0x34/0x70
>>> device_del+0x58/0x30c
>>> device_unregister+0x30/0x7c
>>> i2c_unregister_device+0x84/0x90 [i2c_core]
>>> ssif_platform_remove+0x38/0x98 [ipmi_ssif]
>>> platform_drv_remove+0x2c/0x6c
>>> device_release_driver_internal+0x168/0x1f8
>>> driver_detach+0x50/0xbc
>>> bus_remove_driver+0x74/0xe8
>>> driver_unregister+0x34/0x5c
>>> platform_driver_unregister+0x20/0x2c
>>> cleanup_ipmi_ssif+0x50/0xd82c [ipmi_ssif]
>>> __arm64_sys_delete_module+0x1b4/0x220
>>> el0_svc_handler+0x104/0x160
>>> el0_svc+0x8/0xc
>>> Code: aa1e03e0 aa0203f6 aa0103f7 d503201f (7940e280)
>>> ---[ end trace 09f0e34cce8e2d8c ]---
>>> Kernel panic - not syncing: Fatal exception
>>> SMP: stopping secondary CPUs
>>> Kernel Offset: disabled
>>> CPU features: 0x23800c38
>>>
>>> So track the clients that the SSIF driver adds and only remove
>>> those.
>>>
>>> Reported-by: George Cherian <george.cherian@...ium.com>
>>> Signed-off-by: Corey Minyard <cminyard@...sta.com>
>>> ---
>>> drivers/char/ipmi/ipmi_ssif.c | 17 ++++++-----------
>>> 1 file changed, 6 insertions(+), 11 deletions(-)
>>>
>>> George, your fix was close, but not quite right. The following
>>> should fix the problem, obvious in hindsight :-). Thanks for working
>>> with me on this.
>>>
>> Thanks Corey!!!
>> This works for me now.
>>
>
> Thanks. Can I add a Tested-by: from you?
Yes.
Tested-by: George Cherian <george.cherian@...ium.com>
Can you CC this to stable too.
-George
>
> -corey
>
>>> -corey
>>>
>>> diff --git a/drivers/char/ipmi/ipmi_ssif.c
>>> b/drivers/char/ipmi/ipmi_ssif.c
>>> index e7e8b86..ca4f7c4 100644
>>> --- a/drivers/char/ipmi/ipmi_ssif.c
>>> +++ b/drivers/char/ipmi/ipmi_ssif.c
>>> @@ -182,6 +182,8 @@ struct ssif_addr_info {
>>> struct device *dev;
>>> struct i2c_client *client;
>>>
>>> + struct i2c_client *added_client;
>>> +
>>> struct mutex clients_mutex;
>>> struct list_head clients;
>>>
>>> @@ -1639,15 +1641,7 @@ static int ssif_probe(struct i2c_client
>>> *client, const struct i2c_device_id *id)
>>>
>>> out:
>>> if (rv) {
>>> - /*
>>> - * Note that if addr_info->client is assigned, we
>>> - * leave it. The i2c client hangs around even if we
>>> - * return a failure here, and the failure here is not
>>> - * propagated back to the i2c code. This seems to be
>>> - * design intent, strange as it may be. But if we
>>> - * don't leave it, ssif_platform_remove will not remove
>>> - * the client like it should.
>>> - */
>>> + addr_info->client = NULL;
>>> dev_err(&client->dev, "Unable to start IPMI SSIF:
>>> %d\n", rv);
>>> kfree(ssif_info);
>>> }
>>> @@ -1667,7 +1661,8 @@ static int ssif_adapter_handler(struct device
>>> *adev, void *opaque)
>>> if (adev->type != &i2c_adapter_type)
>>> return 0;
>>>
>>> - i2c_new_device(to_i2c_adapter(adev), &addr_info->binfo);
>>> + addr_info->added_client = i2c_new_device(to_i2c_adapter(adev),
>>> + &addr_info->binfo);
>>>
>>> if (!addr_info->adapter_name)
>>> return 1; /* Only try the first I2C adapter by
>>> default. */
>>> @@ -1840,7 +1835,7 @@ static int ssif_platform_remove(struct
>>> platform_device *dev)
>>> return 0;
>>>
>>> mutex_lock(&ssif_infos_mutex);
>>> - i2c_unregister_device(addr_info->client);
>>> + i2c_unregister_device(addr_info->added_client);
>>>
>>> list_del(&addr_info->link);
>>> kfree(addr_info);
>>> --
>>> 2.7.4
>>>
>
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