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/cdrom/cdrom-standard.rst | 11 ++++++ Documentation/userspace-api/ioctl/cdrom.rst | 3 ++ drivers/cdrom/cdrom.c | 59 +++++++++++++++++++++++++++-- include/linux/cdrom.h | 1 + include/uapi/linux/cdrom.h | 19 ++++++++++ 5 files changed, 89 insertions(+), 4 deletions(-) diff --git a/Documentation/cdrom/cdrom-standard.rst b/Documentation/cdrom/cdrom-standard.rst index 5845960ca38218..52ea7b6b2fe8eb 100644 --- a/Documentation/cdrom/cdrom-standard.rst +++ b/Documentation/cdrom/cdrom-standard.rst @@ -907,6 +907,17 @@ commands can be identified by the underscores in their names. specifies the slot for which the information is given. The special value *CDSL_CURRENT* requests that information about the currently selected slot be returned. +`CDROM_TIMED_MEDIA_CHANGE` + Checks whether the disc has been changed since a user supplied time + and returns the time of the last disc change. + + *arg* is a pointer to a *cdrom_timed_media_change_info* struct. + *arg->last_media_change* may be set by calling code to signal + the timestamp of the last known media change (by the caller). + Upon successful return, this ioctl call will set + *arg->last_media_change* to the latest media change timestamp (in ms) + known by the kernel/driver and set *arg->has_changed* to 1 if + that timestamp is more recent than the timestamp set by the caller. `CDROM_DRIVE_STATUS` Returns the status of the drive by a call to *drive_status()*. Return values are defined in cdrom_drive_status_. diff --git a/Documentation/userspace-api/ioctl/cdrom.rst b/Documentation/userspace-api/ioctl/cdrom.rst index 3b4c0506de466a..bac5bbf93ca0b8 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 diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c index bd2e5b1560f525..89a68457820ab8 100644 --- a/drivers/cdrom/cdrom.c +++ b/drivers/cdrom/cdrom.c @@ -344,6 +344,12 @@ static void cdrom_sysctl_register(void); static LIST_HEAD(cdrom_list); +static void signal_media_change(struct cdrom_device_info *cdi) +{ + cdi->mc_flags = 0x3; /* set media changed bits, on both queues */ + cdi->last_media_change_ms = ktime_to_ms(ktime_get()); +} + int cdrom_dummy_generic_packet(struct cdrom_device_info *cdi, struct packet_command *cgc) { @@ -616,6 +622,7 @@ int register_cdrom(struct gendisk *disk, struct cdrom_device_info *cdi) ENSURE(cdo, generic_packet, CDC_GENERIC_PACKET); cdi->mc_flags = 0; cdi->options = CDO_USE_FFLAGS; + cdi->last_media_change_ms = ktime_to_ms(ktime_get()); if (autoclose == 1 && CDROM_CAN(CDC_CLOSE_TRAY)) cdi->options |= (int) CDO_AUTO_CLOSE; @@ -1421,8 +1428,7 @@ static int cdrom_select_disc(struct cdrom_device_info *cdi, int slot) cdi->ops->check_events(cdi, 0, slot); if (slot == CDSL_NONE) { - /* set media changed bits, on both queues */ - cdi->mc_flags = 0x3; + signal_media_change(cdi); return cdrom_load_unload(cdi, -1); } @@ -1455,7 +1461,7 @@ static int cdrom_select_disc(struct cdrom_device_info *cdi, int slot) slot = curslot; /* set media changed bits on both queues */ - cdi->mc_flags = 0x3; + signal_media_change(cdi); if ((ret = cdrom_load_unload(cdi, slot))) return ret; @@ -1521,7 +1527,7 @@ int media_changed(struct cdrom_device_info *cdi, int queue) cdi->ioctl_events = 0; if (changed) { - cdi->mc_flags = 0x3; /* set bit on both queues */ + signal_media_change(cdi); ret |= 1; cdi->media_written = 0; } @@ -2336,6 +2342,49 @@ static int cdrom_ioctl_media_changed(struct cdrom_device_info *cdi, return ret; } +/* + * Media change detection with timing information. + * + * arg is a pointer to a cdrom_timed_media_change_info struct. + * arg->last_media_change may be set by calling code to signal + * the timestamp (in ms) of the last known media change (by the caller). + * Upon successful return, ioctl call will set arg->last_media_change + * to the latest media change timestamp known by the kernel/driver + * and set arg->has_changed to 1 if that timestamp is more recent + * than the timestamp set by the caller. + */ +static int cdrom_ioctl_timed_media_change(struct cdrom_device_info *cdi, + unsigned long arg) +{ + int ret; + struct cdrom_timed_media_change_info __user *info; + struct cdrom_timed_media_change_info tmp_info; + + if (!CDROM_CAN(CDC_MEDIA_CHANGED)) + return -ENOSYS; + + info = (struct cdrom_timed_media_change_info __user *)arg; + cd_dbg(CD_DO_IOCTL, "entering CDROM_TIMED_MEDIA_CHANGE\n"); + + ret = cdrom_ioctl_media_changed(cdi, CDSL_CURRENT); + if (ret < 0) + return ret; + + if (copy_from_user(&tmp_info, info, sizeof(tmp_info)) != 0) + return -EFAULT; + + tmp_info.media_flags = 0; + if (tmp_info.last_media_change - cdi->last_media_change_ms < 0) + tmp_info.media_flags |= MEDIA_CHANGED_FLAG; + + tmp_info.last_media_change = cdi->last_media_change_ms; + + if (copy_to_user(info, &tmp_info, sizeof(*info)) != 0) + return -EFAULT; + + return 0; +} + static int cdrom_ioctl_set_options(struct cdrom_device_info *cdi, unsigned long arg) { @@ -3313,6 +3362,8 @@ int cdrom_ioctl(struct cdrom_device_info *cdi, struct block_device *bdev, return cdrom_ioctl_eject_sw(cdi, arg); case CDROM_MEDIA_CHANGED: return cdrom_ioctl_media_changed(cdi, arg); + case CDROM_TIMED_MEDIA_CHANGE: + return cdrom_ioctl_timed_media_change(cdi, arg); case CDROM_SET_OPTIONS: return cdrom_ioctl_set_options(cdi, arg); case CDROM_CLEAR_OPTIONS: diff --git a/include/linux/cdrom.h b/include/linux/cdrom.h index c4fef00abdf38f..0a89f111e00e1c 100644 --- a/include/linux/cdrom.h +++ b/include/linux/cdrom.h @@ -64,6 +64,7 @@ struct cdrom_device_info { int for_data; int (*exit)(struct cdrom_device_info *); int mrw_mode_page; + __s64 last_media_change_ms; }; struct cdrom_device_ops { diff --git a/include/uapi/linux/cdrom.h b/include/uapi/linux/cdrom.h index 6c34f6e2f1f71e..804ff8d98f710c 100644 --- a/include/uapi/linux/cdrom.h +++ b/include/uapi/linux/cdrom.h @@ -147,6 +147,8 @@ #define CDROM_NEXT_WRITABLE 0x5394 /* get next writable block */ #define CDROM_LAST_WRITTEN 0x5395 /* get last block written on disc */ +#define CDROM_TIMED_MEDIA_CHANGE 0x5396 /* get the timestamp of the last media change */ + /******************************************************* * CDROM IOCTL structures *******************************************************/ @@ -295,6 +297,23 @@ struct cdrom_generic_command }; }; +/* This struct is used by CDROM_TIMED_MEDIA_CHANGE */ +struct cdrom_timed_media_change_info { + __s64 last_media_change; /* Timestamp of the last detected media + * change in ms. May be set by caller, + * updated upon successful return of + * ioctl. + */ + __u64 media_flags; /* Flags returned by ioctl to indicate + * media status. + */ +}; +#define MEDIA_CHANGED_FLAG 0x1 /* Last detected media change was more + * recent than last_media_change set by + * caller. + */ +/* other bits of media_flags available for future use */ + /* * A CD-ROM physical sector size is 2048, 2052, 2056, 2324, 2332, 2336, * 2340, or 2352 bytes long. -- cgit 1.2.3-korg 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(-) diff --git a/Documentation/userspace-api/ioctl/cdrom.rst b/Documentation/userspace-api/ioctl/cdrom.rst index bac5bbf93ca0b8..682948fc88a34a 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 1.2.3-korg From bbc3925cf696422492ebdaba386e61450fa2294c Mon Sep 17 00:00:00 2001 From: luo penghao Date: Thu, 21 Oct 2021 08:46:21 +0100 Subject: cdrom: Remove redundant variable and its assignment Variable is not used in functions, and its assignment is redundant too. So it should be deleted. Also the inner-most set of parentheses is no longer needed. The clang_analyzer complains as follows: drivers/cdrom/cdrom.c:877: warning: Although the value stored to 'ret' is used in the enclosing expression, the value is never actually read from 'ret'. Reported-by: Zeal Robot Signed-off-by: luo penghao Link: https://lore.kernel.org/all/20211020024229.1036219-1-luo.penghao@zte.com.cn Signed-off-by: Phillip Potter Link: https://lore.kernel.org/r/20211021074621.901-1-phil@philpotter.co.uk Signed-off-by: Jens Axboe --- drivers/cdrom/cdrom.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c index 89a68457820ab8..9877e413fce39d 100644 --- a/drivers/cdrom/cdrom.c +++ b/drivers/cdrom/cdrom.c @@ -871,7 +871,7 @@ static void cdrom_mmc3_profile(struct cdrom_device_info *cdi) { struct packet_command cgc; char buffer[32]; - int ret, mmc3_profile; + int mmc3_profile; init_cdrom_command(&cgc, buffer, sizeof(buffer), CGC_DATA_READ); @@ -881,7 +881,7 @@ static void cdrom_mmc3_profile(struct cdrom_device_info *cdi) cgc.cmd[8] = sizeof(buffer); /* Allocation Length */ cgc.quiet = 1; - if ((ret = cdi->ops->generic_packet(cdi, &cgc))) + if (cdi->ops->generic_packet(cdi, &cgc)) mmc3_profile = 0xffff; else mmc3_profile = (buffer[6] << 8) | buffer[7]; -- cgit 1.2.3-korg