On 08.03.21 15:36, Greg KH wrote:
On Mon, Mar 08, 2021 at 04:18:03PM +0200, Adrian Catangiu wrote:+static struct miscdevice sysgenid_misc = { + .minor = MISC_DYNAMIC_MINOR, + .name = "sysgenid", + .fops = &fops, +};Much cleaner, but:+static int __init sysgenid_init(void) +{ + int ret; + + sysgenid_data.map_buf = get_zeroed_page(GFP_KERNEL); + if (!sysgenid_data.map_buf) + return -ENOMEM; + + atomic_set(&sysgenid_data.generation_counter, 0); + atomic_set(&sysgenid_data.outdated_watchers, 0); + init_waitqueue_head(&sysgenid_data.read_waitq); + init_waitqueue_head(&sysgenid_data.outdated_waitq); + spin_lock_init(&sysgenid_data.lock); + + ret = misc_register(&sysgenid_misc); + if (ret < 0) { + pr_err("misc_register() failed for sysgenid\n"); + goto err; + } + + return 0; + +err: + free_pages(sysgenid_data.map_buf, 0); + sysgenid_data.map_buf = 0; + + return ret; +} + +static void __exit sysgenid_exit(void) +{ + misc_deregister(&sysgenid_misc); + free_pages(sysgenid_data.map_buf, 0); + sysgenid_data.map_buf = 0; +} + +module_init(sysgenid_init); +module_exit(sysgenid_exit);So you do this for any bit of hardware that happens to be out there? Will that really work? You do not have any hwid to trigger off of to know that this is a valid device you can handle?
The interface is already useful in a pure container context where the generation change request is triggered by software.
And yes, there are hardware triggers, but Michael was quite unhappy about potential races between VMGenID change and SysGenID change and thus wanted to ideally separate the interfaces. So we went ahead and isolated the SysGenID one, as it's already useful as is.
Hardware drivers to inject change events into SysGenID can then follow later, for all different hardware platforms. But SysGenID as in this patch is a completely hardware agnostic concept.
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