Re: [BUG] tpm: prolonged stall in vtpm_proxy_fops_release() on Linux 7.3

[Stefan Berger]

On 11/8/26 12:15 PM, 铮 wrote:
> Hi Stefan,
>
> Thank you for the patch
> ("tpm: tpm_vtpm_proxy: Set STATE_OPENED_FLAG before inode is created").
> We applied and tested it, and we have also reproduced the boot warning
> Stefan reported and identified a sufficient condition for
> it (running without KVM acceleration). Two findings first; "Where to
> look" at the end points to the exact files in our repository.
>
> 1. Your patch does not change the outcome of the hang
[...]

> v7.4-rc1 is affected as well: drivers/char/tpm/tpm_vtpm_proxy.c is
> unchanged between v7.3.0 and v7.4-rc1 (empty diff), and the same
> reproduction hangs there 1/1 (t=402s, same signature).

I have a hard time reading these .prog files. Are you closing the server 
side file descriptor you are getting back via the ioctl to /dev/tpm? 
Have a look below. If not, that could be the reason why its hanging. If 
you close it, it should clear the STATE_OPENED_FLAG and wake up any 
client waiting for a response.

/**
 * struct vtpm_proxy_new_dev - parameter structure for the
 *                             %VTPM_PROXY_IOC_NEW_DEV ioctl
 * @flags:	flags for the proxy TPM
 * @tpm_num:	index of the TPM device
 * @fd:		the file descriptor used by the proxy TPM
 * @major:	the major number of the TPM device
 * @minor:	the minor number of the TPM device
 */
struct vtpm_proxy_new_dev {
	__u32 flags;         /* input */
	__u32 tpm_num;       /* output */
	__u32 fd;            /* output */    <--- this one here
	__u32 major;         /* output */
	__u32 minor;         /* output */
};


  Stefan