diff options
author | Tejun Heo <tj@kernel.org> | 2010-12-08 20:57:38 +0100 |
---|---|---|
committer | Jens Axboe <jaxboe@fusionio.com> | 2010-12-16 17:53:38 +0100 |
commit | 2d9217296bfa6fdc0d3707264076e5296faffdbd (patch) | |
tree | ea929977770d95a47a4e7cbf15f13fb0e3d8dcad /drivers/cdrom/cdrom.c | |
parent | implement in-kernel gendisk events handling (diff) | |
download | linux-2d9217296bfa6fdc0d3707264076e5296faffdbd.tar.xz linux-2d9217296bfa6fdc0d3707264076e5296faffdbd.zip |
cdrom: add ->check_events() support
In principle, cdrom just needs to pass through ->check_events() but
CDROM_MEDIA_CHANGED ioctl makes things a bit more complex. Just as
with ->media_changed() support, cdrom code needs to buffer the events
and serve them to ioctl and vfs as requested.
As the code has to deal with both ->check_events() and
->media_changed(), and vfs and ioctl event buffering, this patch adds
check_events caching on top of the existing cdi->mc_flags buffering.
It may be a good idea to deprecate CDROM_MEDIA_CHANGED ioctl and
remove all this mess.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'drivers/cdrom/cdrom.c')
-rw-r--r-- | drivers/cdrom/cdrom.c | 55 |
1 files changed, 52 insertions, 3 deletions
diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c index af13c62dc473..1ea8f8d363c6 100644 --- a/drivers/cdrom/cdrom.c +++ b/drivers/cdrom/cdrom.c @@ -1348,7 +1348,10 @@ static int cdrom_select_disc(struct cdrom_device_info *cdi, int slot) if (!CDROM_CAN(CDC_SELECT_DISC)) return -EDRIVE_CANT_DO_THIS; - (void) cdi->ops->media_changed(cdi, slot); + if (cdi->ops->check_events) + cdi->ops->check_events(cdi, 0, slot); + else + cdi->ops->media_changed(cdi, slot); if (slot == CDSL_NONE) { /* set media changed bits, on both queues */ @@ -1392,6 +1395,41 @@ static int cdrom_select_disc(struct cdrom_device_info *cdi, int slot) return slot; } +/* + * As cdrom implements an extra ioctl consumer for media changed + * event, it needs to buffer ->check_events() output, such that event + * is not lost for both the usual VFS and ioctl paths. + * cdi->{vfs|ioctl}_events are used to buffer pending events for each + * path. + * + * XXX: Locking is non-existent. cdi->ops->check_events() can be + * called in parallel and buffering fields are accessed without any + * exclusion. The original media_changed code had the same problem. + * It might be better to simply deprecate CDROM_MEDIA_CHANGED ioctl + * and remove this cruft altogether. It doesn't have much usefulness + * at this point. + */ +static void cdrom_update_events(struct cdrom_device_info *cdi, + unsigned int clearing) +{ + unsigned int events; + + events = cdi->ops->check_events(cdi, clearing, CDSL_CURRENT); + cdi->vfs_events |= events; + cdi->ioctl_events |= events; +} + +unsigned int cdrom_check_events(struct cdrom_device_info *cdi, + unsigned int clearing) +{ + unsigned int events; + + cdrom_update_events(cdi, clearing); + events = cdi->vfs_events; + cdi->vfs_events = 0; + return events; +} + /* We want to make media_changed accessible to the user through an * ioctl. The main problem now is that we must double-buffer the * low-level implementation, to assure that the VFS and the user both @@ -1403,15 +1441,26 @@ int media_changed(struct cdrom_device_info *cdi, int queue) { unsigned int mask = (1 << (queue & 1)); int ret = !!(cdi->mc_flags & mask); + bool changed; if (!CDROM_CAN(CDC_MEDIA_CHANGED)) - return ret; + return ret; + /* changed since last call? */ - if (cdi->ops->media_changed(cdi, CDSL_CURRENT)) { + if (cdi->ops->check_events) { + BUG_ON(!queue); /* shouldn't be called from VFS path */ + cdrom_update_events(cdi, DISK_EVENT_MEDIA_CHANGE); + changed = cdi->ioctl_events & DISK_EVENT_MEDIA_CHANGE; + cdi->ioctl_events = 0; + } else + changed = cdi->ops->media_changed(cdi, CDSL_CURRENT); + + if (changed) { cdi->mc_flags = 0x3; /* set bit on both queues */ ret |= 1; cdi->media_written = 0; } + cdi->mc_flags &= ~mask; /* clear bit */ return ret; } |