From 67f1e027c27054e641584655020a417eaac9cb3a Mon Sep 17 00:00:00 2001 From: Lukas Prediger Date: Tue, 14 Sep 2021 00:09:42 +0100 Subject: drivers/cdrom: improved ioctl for media change detection The current implementation of the CDROM_MEDIA_CHANGED ioctl relies on global state, meaning that only one process can detect a disc change while the ioctl call will return 0 for other calling processes afterwards (see bug 213267). This introduces a new cdrom ioctl, CDROM_TIMED_MEDIA_CHANGE, that works by maintaining a timestamp of the last detected disc change instead of a boolean flag: Processes calling this ioctl command can provide a timestamp of the last disc change known to them and receive an indication whether the disc was changed since then and the updated timestamp. I considered fixing the buggy behavior in the original CDROM_MEDIA_CHANGED ioctl but that would require maintaining state for each calling process in the kernel, which seems like a worse solution than introducing this new ioctl. Signed-off-by: Lukas Prediger Link: https://lore.kernel.org/all/20210912191207.74449-1-lumip@lumip.de Signed-off-by: Phillip Potter Link: https://lore.kernel.org/r/20210913230942.1188-1-phil@philpotter.co.uk Signed-off-by: Jens Axboe --- Documentation/userspace-api/ioctl/cdrom.rst | 3 +++ 1 file changed, 3 insertions(+) (limited to 'Documentation/userspace-api') diff --git a/Documentation/userspace-api/ioctl/cdrom.rst b/Documentation/userspace-api/ioctl/cdrom.rst index 3b4c0506de46..bac5bbf93ca0 100644 --- a/Documentation/userspace-api/ioctl/cdrom.rst +++ b/Documentation/userspace-api/ioctl/cdrom.rst @@ -54,6 +54,9 @@ are as follows: CDROM_SELECT_SPEED Set the CD-ROM speed CDROM_SELECT_DISC Select disc (for juke-boxes) CDROM_MEDIA_CHANGED Check is media changed + CDROM_TIMED_MEDIA_CHANGE Check if media changed + since given time + (struct cdrom_timed_media_change_info) CDROM_DRIVE_STATUS Get tray position, etc. CDROM_DISC_STATUS Get disc type, etc. CDROM_CHANGER_NSLOTS Get number of slots -- cgit v1.2.3-70-g09d2 From 9c03fee7e3fa01ca86d9d6195994cd9e6d24264b Mon Sep 17 00:00:00 2001 From: Phillip Potter Date: Fri, 8 Oct 2021 00:17:20 +0100 Subject: cdrom: docs: reformat table in Documentation/userspace-api/ioctl/cdrom.rst Add extra space to the first column of ioctl values table, and also realign the text in the second column, to fix a documentation build warning introduced by: commit 67f1e027c270 ("drivers/cdrom: improved ioctl for media change detection") Suggested-by: Randy Dunlap Fixes: 67f1e027c270 ("drivers/cdrom: improved ioctl for media change detection") Signed-off-by: Phillip Potter Reviewed-by: Randy Dunlap Link: https://lore.kernel.org/r/20211007231720.31997-1-phil@philpotter.co.uk Signed-off-by: Jens Axboe --- Documentation/userspace-api/ioctl/cdrom.rst | 116 ++++++++++++++-------------- 1 file changed, 58 insertions(+), 58 deletions(-) (limited to 'Documentation/userspace-api') diff --git a/Documentation/userspace-api/ioctl/cdrom.rst b/Documentation/userspace-api/ioctl/cdrom.rst index bac5bbf93ca0..682948fc88a3 100644 --- a/Documentation/userspace-api/ioctl/cdrom.rst +++ b/Documentation/userspace-api/ioctl/cdrom.rst @@ -13,64 +13,64 @@ in drivers/cdrom/cdrom.c and drivers/block/scsi_ioctl.c ioctl values are listed in . As of this writing, they are as follows: - ====================== =============================================== - CDROMPAUSE Pause Audio Operation - CDROMRESUME Resume paused Audio Operation - CDROMPLAYMSF Play Audio MSF (struct cdrom_msf) - CDROMPLAYTRKIND Play Audio Track/index (struct cdrom_ti) - CDROMREADTOCHDR Read TOC header (struct cdrom_tochdr) - CDROMREADTOCENTRY Read TOC entry (struct cdrom_tocentry) - CDROMSTOP Stop the cdrom drive - CDROMSTART Start the cdrom drive - CDROMEJECT Ejects the cdrom media - CDROMVOLCTRL Control output volume (struct cdrom_volctrl) - CDROMSUBCHNL Read subchannel data (struct cdrom_subchnl) - CDROMREADMODE2 Read CDROM mode 2 data (2336 Bytes) - (struct cdrom_read) - CDROMREADMODE1 Read CDROM mode 1 data (2048 Bytes) - (struct cdrom_read) - CDROMREADAUDIO (struct cdrom_read_audio) - CDROMEJECT_SW enable(1)/disable(0) auto-ejecting - CDROMMULTISESSION Obtain the start-of-last-session - address of multi session disks - (struct cdrom_multisession) - CDROM_GET_MCN Obtain the "Universal Product Code" - if available (struct cdrom_mcn) - CDROM_GET_UPC Deprecated, use CDROM_GET_MCN instead. - CDROMRESET hard-reset the drive - CDROMVOLREAD Get the drive's volume setting - (struct cdrom_volctrl) - CDROMREADRAW read data in raw mode (2352 Bytes) - (struct cdrom_read) - CDROMREADCOOKED read data in cooked mode - CDROMSEEK seek msf address - CDROMPLAYBLK scsi-cd only, (struct cdrom_blk) - CDROMREADALL read all 2646 bytes - CDROMGETSPINDOWN return 4-bit spindown value - CDROMSETSPINDOWN set 4-bit spindown value - CDROMCLOSETRAY pendant of CDROMEJECT - CDROM_SET_OPTIONS Set behavior options - CDROM_CLEAR_OPTIONS Clear behavior options - CDROM_SELECT_SPEED Set the CD-ROM speed - CDROM_SELECT_DISC Select disc (for juke-boxes) - CDROM_MEDIA_CHANGED Check is media changed - CDROM_TIMED_MEDIA_CHANGE Check if media changed - since given time - (struct cdrom_timed_media_change_info) - CDROM_DRIVE_STATUS Get tray position, etc. - CDROM_DISC_STATUS Get disc type, etc. - CDROM_CHANGER_NSLOTS Get number of slots - CDROM_LOCKDOOR lock or unlock door - CDROM_DEBUG Turn debug messages on/off - CDROM_GET_CAPABILITY get capabilities - CDROMAUDIOBUFSIZ set the audio buffer size - DVD_READ_STRUCT Read structure - DVD_WRITE_STRUCT Write structure - DVD_AUTH Authentication - CDROM_SEND_PACKET send a packet to the drive - CDROM_NEXT_WRITABLE get next writable block - CDROM_LAST_WRITTEN get last block written on disc - ====================== =============================================== + ======================== =============================================== + CDROMPAUSE Pause Audio Operation + CDROMRESUME Resume paused Audio Operation + CDROMPLAYMSF Play Audio MSF (struct cdrom_msf) + CDROMPLAYTRKIND Play Audio Track/index (struct cdrom_ti) + CDROMREADTOCHDR Read TOC header (struct cdrom_tochdr) + CDROMREADTOCENTRY Read TOC entry (struct cdrom_tocentry) + CDROMSTOP Stop the cdrom drive + CDROMSTART Start the cdrom drive + CDROMEJECT Ejects the cdrom media + CDROMVOLCTRL Control output volume (struct cdrom_volctrl) + CDROMSUBCHNL Read subchannel data (struct cdrom_subchnl) + CDROMREADMODE2 Read CDROM mode 2 data (2336 Bytes) + (struct cdrom_read) + CDROMREADMODE1 Read CDROM mode 1 data (2048 Bytes) + (struct cdrom_read) + CDROMREADAUDIO (struct cdrom_read_audio) + CDROMEJECT_SW enable(1)/disable(0) auto-ejecting + CDROMMULTISESSION Obtain the start-of-last-session + address of multi session disks + (struct cdrom_multisession) + CDROM_GET_MCN Obtain the "Universal Product Code" + if available (struct cdrom_mcn) + CDROM_GET_UPC Deprecated, use CDROM_GET_MCN instead. + CDROMRESET hard-reset the drive + CDROMVOLREAD Get the drive's volume setting + (struct cdrom_volctrl) + CDROMREADRAW read data in raw mode (2352 Bytes) + (struct cdrom_read) + CDROMREADCOOKED read data in cooked mode + CDROMSEEK seek msf address + CDROMPLAYBLK scsi-cd only, (struct cdrom_blk) + CDROMREADALL read all 2646 bytes + CDROMGETSPINDOWN return 4-bit spindown value + CDROMSETSPINDOWN set 4-bit spindown value + CDROMCLOSETRAY pendant of CDROMEJECT + CDROM_SET_OPTIONS Set behavior options + CDROM_CLEAR_OPTIONS Clear behavior options + CDROM_SELECT_SPEED Set the CD-ROM speed + CDROM_SELECT_DISC Select disc (for juke-boxes) + CDROM_MEDIA_CHANGED Check is media changed + CDROM_TIMED_MEDIA_CHANGE Check if media changed + since given time + (struct cdrom_timed_media_change_info) + CDROM_DRIVE_STATUS Get tray position, etc. + CDROM_DISC_STATUS Get disc type, etc. + CDROM_CHANGER_NSLOTS Get number of slots + CDROM_LOCKDOOR lock or unlock door + CDROM_DEBUG Turn debug messages on/off + CDROM_GET_CAPABILITY get capabilities + CDROMAUDIOBUFSIZ set the audio buffer size + DVD_READ_STRUCT Read structure + DVD_WRITE_STRUCT Write structure + DVD_AUTH Authentication + CDROM_SEND_PACKET send a packet to the drive + CDROM_NEXT_WRITABLE get next writable block + CDROM_LAST_WRITTEN get last block written on disc + ======================== =============================================== The information that follows was determined from reading kernel source -- cgit v1.2.3-70-g09d2