Re: [PATCH 2/4] Revert "ide: unexport DISK_EVENT_MEDIA_CHANGE for ide-gd and ide-cd"

[Hannes Reinecke <hare@suse.de>]

On 1/18/19 10:32 PM, Martin Wilck wrote:
> This reverts commit 7eec77a1816a7042591a6cbdb4820e9e7ebffe0e.
> 
> Instead of leaving disk->events completely empty, we now export the supported
> events again, and tell the block layer not to forward events to user space by
> not setting DISK_EVENT_FLAG_UEVENT. This allows the block layer to distinguish
> between devices that for which events should be handled in kernel only, and
> devices which don't support any meda change events at all.
> 
> Cc: Borislav Petkov <bp@alien8.de>
> Signed-off-by: Martin Wilck <mwilck@suse.com>
> ---
>   drivers/ide/ide-cd.c       | 1 +
>   drivers/ide/ide-cd_ioctl.c | 5 +++--
>   drivers/ide/ide-gd.c       | 6 ++++--
>   3 files changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c
> index 1f03884..3b15adc 100644
> --- a/drivers/ide/ide-cd.c
> +++ b/drivers/ide/ide-cd.c
> @@ -1797,6 +1797,7 @@ static int ide_cd_probe(ide_drive_t *drive)
>   	ide_cd_read_toc(drive);
>   	g->fops = &idecd_ops;
>   	g->flags |= GENHD_FL_REMOVABLE | GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE;
> +	g->events = DISK_EVENT_MEDIA_CHANGE;
>   	device_add_disk(&drive->gendev, g, NULL);
>   	return 0;
>   
> diff --git a/drivers/ide/ide-cd_ioctl.c b/drivers/ide/ide-cd_ioctl.c
> index 4a6e1a4..f9f4bac 100644
> --- a/drivers/ide/ide-cd_ioctl.c
> +++ b/drivers/ide/ide-cd_ioctl.c
> @@ -82,8 +82,9 @@ int ide_cdrom_drive_status(struct cdrom_device_info *cdi, int slot_nr)
>   
>   /*
>    * ide-cd always generates media changed event if media is missing, which
> - * makes it impossible to use for proper event reporting, so disk->events
> - * is cleared to 0 and the following function is used only to trigger
> + * makes it impossible to use for proper event reporting, so
> + * DISK_EVENT_FLAG_UEVENT is cleared in disk->events
> + * and the following function is used only to trigger
>    * revalidation and never propagated to userland.
>    */
>   unsigned int ide_cdrom_check_events_real(struct cdrom_device_info *cdi,
> diff --git a/drivers/ide/ide-gd.c b/drivers/ide/ide-gd.c
> index 04e008e..cab8052 100644
> --- a/drivers/ide/ide-gd.c
> +++ b/drivers/ide/ide-gd.c
> @@ -299,8 +299,9 @@ static unsigned int ide_gd_check_events(struct gendisk *disk,
>   	/*
>   	 * The following is used to force revalidation on the first open on
>   	 * removeable devices, and never gets reported to userland as
> -	 * genhd->events is 0.  This is intended as removeable ide disk
> -	 * can't really detect MEDIA_CHANGE events.
> +	 * DISK_EVENT_FLAG_UEVENT isn't set in genhd->events.
> +	 * This is intended as removeable ide disk can't really detect
> +	 * MEDIA_CHANGE events.
>   	 */
>   	ret = drive->dev_flags & IDE_DFLAG_MEDIA_CHANGED;
>   	drive->dev_flags &= ~IDE_DFLAG_MEDIA_CHANGED;
> @@ -417,6 +418,7 @@ static int ide_gd_probe(ide_drive_t *drive)
>   		g->flags = GENHD_FL_REMOVABLE;
>   	g->fops = &ide_gd_ops;
>   	device_add_disk(&drive->gendev, g, NULL);
> +	g->events = DISK_EVENT_MEDIA_CHANGE;
>   	return 0;
>   
>   out_free_disk:
> 
Please set the events mask prior to call device_add_disk(), otherwise 
we'll have a race condition here.

Cheers,

Hannes