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Message-ID: <46F909CA.3030101@st.com>
Date: Tue, 25 Sep 2007 15:14:50 +0200
From: Richard MUSIL <richard.musil@...com>
To: Greg KH <greg@...ah.com>
Cc: linux-kernel@...r.kernel.org, tpmdd-devel@...ts.sourceforge.net
Subject: Re: [PATCH] - TPM device driver layer (tpm.c|h) - repost
Hello all,
sometime ago I submitted patch to TPM layer, originally I thought this
patch could be accepted into kernel (see below). However,
since this did not happen, I wonder, if there are some problems with the
patch or whether I am expected to do/provide something else, in order to
have it accepted.
The patch follows even more below.
Thanks,
Richard
Greg KH wrote:
> On Thu, Aug 23, 2007 at 10:46:55AM +0200, Richard MUSIL wrote:
>> Dear all,
>>
>> I am currently writing virtual TPM device driver. This driver exposes
>> itself and behaves like regular TPM device (i.e. uses TPM layer which is
>> already present in kernel), but instead of talking to hardware it talks
>> to user space.
>
> Heh, I like the idea, I can imagine what it could be used for :)
>
>> What I present below is rather quickfix with least impact on other TPM
>> parts (drivers). The patch uses device->remove callback (of
>> platform_device device) and reroutes this to itself. In this
>> callback it eventually calls vendor callback and finally kfrees all
>> memory resources allocated on its own.
>
> It looks sane to me, nice fixup.
>
> thanks,
>
> greg k-h
>
>From bd80b63ca2e1edb761a3ffcf87bd86c30a44ca5f Mon Sep 17 00:00:00 2001
From: Richard Musil <richard.musil@...com>
Date: Tue, 21 Aug 2007 16:46:06 +0200
Subject: [PATCH] Change in TPM module:
The clean up procedure now uses platform device "release" callback to
handle memory clean up. For this purpose "release" function callback was
added to struct tpm_vendor_specific, so hw device driver provider can get
called when it is safe to remove all allocated resources.
This is supposed to fix a bug in device removal, where device while in
receive function (waiting on timeout) was prone to segfault, if the
tpm_chip struct was unallocated before the timeout expired (in
tpm_remove_hardware).
---
drivers/char/tpm/tpm.c | 46 +++++++++++++++++++++++++++++-----------------
drivers/char/tpm/tpm.h | 2 ++
2 files changed, 31 insertions(+), 17 deletions(-)
diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index 9bb5429..41eba7e 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -1031,18 +1031,13 @@ void tpm_remove_hardware(struct device *dev)
spin_unlock(&driver_lock);
- dev_set_drvdata(dev, NULL);
misc_deregister(&chip->vendor.miscdev);
- kfree(chip->vendor.miscdev.name);
sysfs_remove_group(&dev->kobj, chip->vendor.attr_group);
tpm_bios_log_teardown(chip->bios_dir);
- clear_bit(chip->dev_num, dev_mask);
-
- kfree(chip);
-
- put_device(dev);
+ /* write it this way to be explicit (chip->dev == dev) */
+ put_device(chip->dev);
}
EXPORT_SYMBOL_GPL(tpm_remove_hardware);
@@ -1083,6 +1078,28 @@ int tpm_pm_resume(struct device *dev)
EXPORT_SYMBOL_GPL(tpm_pm_resume);
/*
+ * Once all references to platform device are down to 0,
+ * release all allocated structures.
+ * In case vendor provided release function,
+ * call it too.
+ */
+static void tpm_dev_release(struct device *dev)
+{
+ struct tpm_chip *chip = dev_get_drvdata(dev);
+ /* call vendor release, if defined */
+ if (chip->vendor.release)
+ chip->vendor.release(dev);
+
+ /* it *should* be: chip->release != NULL */
+ if (likely(chip->release))
+ chip->release(dev);
+
+ clear_bit(chip->dev_num, dev_mask);
+ kfree(chip->vendor.miscdev.name);
+ kfree(chip);
+}
+
+/*
* Called from tpm_<specific>.c probe function only for devices
* the driver has determined it should claim. Prior to calling
* this function the specific probe function has called pci_enable_device
@@ -1136,23 +1153,21 @@ struct tpm_chip *tpm_register_hardware(struct device *dev, const struct tpm_vend
chip->vendor.miscdev.parent = dev;
chip->dev = get_device(dev);
+ chip->release = dev->release;
+ dev->release = tpm_dev_release;
+ dev_set_drvdata(dev, chip);
if (misc_register(&chip->vendor.miscdev)) {
dev_err(chip->dev,
"unable to misc_register %s, minor %d\n",
chip->vendor.miscdev.name,
chip->vendor.miscdev.minor);
- put_device(dev);
- clear_bit(chip->dev_num, dev_mask);
- kfree(chip);
- kfree(devname);
+ put_device(chip->dev);
return NULL;
}
spin_lock(&driver_lock);
- dev_set_drvdata(dev, chip);
-
list_add(&chip->list, &tpm_chip_list);
spin_unlock(&driver_lock);
@@ -1160,10 +1175,7 @@ struct tpm_chip *tpm_register_hardware(struct device *dev, const struct tpm_vend
if (sysfs_create_group(&dev->kobj, chip->vendor.attr_group)) {
list_del(&chip->list);
misc_deregister(&chip->vendor.miscdev);
- put_device(dev);
- clear_bit(chip->dev_num, dev_mask);
- kfree(chip);
- kfree(devname);
+ put_device(chip->dev);
return NULL;
}
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index b2e2b00..f1c265e 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -74,6 +74,7 @@ struct tpm_vendor_specific {
int (*send) (struct tpm_chip *, u8 *, size_t);
void (*cancel) (struct tpm_chip *);
u8 (*status) (struct tpm_chip *);
+ void (*release) (struct device *);
struct miscdevice miscdev;
struct attribute_group *attr_group;
struct list_head list;
@@ -106,6 +107,7 @@ struct tpm_chip {
struct dentry **bios_dir;
struct list_head list;
+ void (*release) (struct device *);
};
#define to_tpm_chip(n) container_of(n, struct tpm_chip, vendor)
-- 1.5.3.rc5
-
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