Messages in this thread Patches in this message | | | From | 이범우 <> | Subject | RE: [PATCH] extcon: modify extcon device to be created after driver data is set | Date | Wed, 27 Apr 2022 11:12:26 +0900 |
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Hi chanwoo.
Thank you for your review.
Actually, I thought the same thing as you first. However, it was a problem because dev->devres_lock was not initialized and devm_kcalloc was used, and this patch was created instead of using kcalloc instead of devm_kcalloc.
In your opinion, if I use kcalloc instead of devm_kcalloc, there will be no problem. But, I think the code of the following part should be supplemented.
1. alloc edev->nh when edev->max_supported is none zero. @@ -1224,19 +1224,14 @@ int extcon_dev_register(struct extcon_dev *edev) + if (edev->max_supported) { + edev->nh = kcalloc(edev->max_supported, sizeof(*edev->nh), + GFP_KERNEL); + if (!edev->nh) { + ret = -ENOMEM; + goto err_alloc_nh; + } } 2. free evdev->nh when device unregister. @@ -1314,6 +1318,7 @@ void extcon_dev_unregister(struct extcon_dev *edev) if (edev->max_supported) { kfree(edev->extcon_dev_type.groups); kfree(edev->cables); + kfree(edev->nh); }
I will re-raise commit after testing. Please let me know if you have additional concern.
Best Regards, Bumwoo Lee. -----Original Message----- From: Chanwoo Choi <cwchoi00@gmail.com> Sent: Wednesday, April 27, 2022 2:09 AM To: bumwoo lee <bw365.lee@samsung.com>; MyungJoo Ham <myungjoo.ham@samsung.com>; Chanwoo Choi <cw00.choi@samsung.com>; linux-kernel@vger.kernel.org Subject: Re: [PATCH] extcon: modify extcon device to be created after driver data is set Hi Bumwoo,
Firstly, I'm sorry for late replay.
On 22. 3. 31. 12:03, bumwoo lee wrote: > Currently, someone can invoke the sysfs such as state_show() > intermittently before set_drvdata() is done. > And it can be a cause of kernel Oops because of edev is Null at that time. > So modified the driver registration to after setting drviver data. > > - Oops's backtrace. > > Backtrace: > [<c067865c>] (state_show) from [<c05222e8>] (dev_attr_show) > [<c05222c0>] (dev_attr_show) from [<c02c66e0>] (sysfs_kf_seq_show) > [<c02c6648>] (sysfs_kf_seq_show) from [<c02c496c>] (kernfs_seq_show) > [<c02c4938>] (kernfs_seq_show) from [<c025e2a0>] (seq_read) > [<c025e11c>] (seq_read) from [<c02c50a0>] (kernfs_fop_read) > [<c02c5064>] (kernfs_fop_read) from [<c0231cac>] (__vfs_read) > [<c0231c5c>] (__vfs_read) from [<c0231ee0>] (vfs_read) [<c0231e34>] > (vfs_read) from [<c0232464>] (ksys_read) [<c02323f0>] (ksys_read) from > [<c02324fc>] (sys_read) [<c02324e4>] (sys_read) from [<c00091d0>] > (__sys_trace_return) > > Signed-off-by: bumwoo lee <bw365.lee@samsung.com> > --- > drivers/extcon/extcon.c | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) > > diff --git a/drivers/extcon/extcon.c b/drivers/extcon/extcon.c index > d27cd9f88f86..74fee04bd764 100644 > --- a/drivers/extcon/extcon.c > +++ b/drivers/extcon/extcon.c > @@ -1224,18 +1224,13 @@ int extcon_dev_register(struct extcon_dev *edev) > edev->dev.type = &edev->extcon_dev_type; > } > > - ret = device_register(&edev->dev); > - if (ret) { > - put_device(&edev->dev); > - goto err_dev; > - } > + device_initialize(&edev->dev); > > spin_lock_init(&edev->lock); > edev->nh = devm_kcalloc(&edev->dev, edev->max_supported, > sizeof(*edev->nh), GFP_KERNEL);
Actually, I'm not sure that it is proper to use 'edev->dev' by devm_kcalloc before device_add. When error happen between device_initialize and device_add, I think that it is not properly handled such as free the allocated memory automatically.
> if (!edev->nh) { > ret = -ENOMEM; > - device_unregister(&edev->dev); > goto err_dev; > } > > @@ -1251,9 +1246,14 @@ int extcon_dev_register(struct extcon_dev *edev) > list_add(&edev->entry, &extcon_dev_list); > mutex_unlock(&extcon_dev_list_lock); > > + ret = device_add(&edev->dev); > + if (ret) > + goto err_dev;
On this case, need to delete entry from extcon_dev_list by using list_del.
> + > return 0; > > err_dev: > + put_device(&edev->dev); > if (edev->max_supported) > kfree(edev->extcon_dev_type.groups); > err_alloc_groups:
I recommend that move device_register() position after dev_set_drvdata. And then use kcalloc instead of devm_kcalloc as following:
diff --git a/drivers/extcon/extcon.c b/drivers/extcon/extcon.c index d27cd9f88f86..80e5bfec1131 100644 --- a/drivers/extcon/extcon.c +++ b/drivers/extcon/extcon.c @@ -1224,19 +1224,11 @@ int extcon_dev_register(struct extcon_dev *edev) edev->dev.type = &edev->extcon_dev_type; }
- ret = device_register(&edev->dev); - if (ret) { - put_device(&edev->dev); - goto err_dev; - } - spin_lock_init(&edev->lock); - edev->nh = devm_kcalloc(&edev->dev, edev->max_supported, - sizeof(*edev->nh), GFP_KERNEL); + edev->nh = kcalloc(edev->max_supported, sizeof(*edev->nh), GFP_KERNEL); if (!edev->nh) { ret = -ENOMEM; - device_unregister(&edev->dev); - goto err_dev; + goto err_alloc_nh; }
for (index = 0; index < edev->max_supported; index++) @@ -1247,6 +1239,12 @@ int extcon_dev_register(struct extcon_dev *edev) dev_set_drvdata(&edev->dev, edev); edev->state = 0;
+ ret = device_register(&edev->dev); + if (ret) { + put_device(&edev->dev); + goto err_dev; + } + mutex_lock(&extcon_dev_list_lock); list_add(&edev->entry, &extcon_dev_list); mutex_unlock(&extcon_dev_list_lock); @@ -1254,6 +1252,9 @@ int extcon_dev_register(struct extcon_dev *edev) return 0;
err_dev: + if (edev->max_supported) + kfree(edev->nh); +err_alloc_nh: if (edev->max_supported) kfree(edev->extcon_dev_type.groups); err_alloc_groups: @@ -1314,6 +1315,7 @@ void extcon_dev_unregister(struct extcon_dev *edev) if (edev->max_supported) { kfree(edev->extcon_dev_type.groups); kfree(edev->cables); + kfree(edev->nh); }
put_device(&edev->dev);
-- Best Regards, Samsung Electronics Chanwoo Choi
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