Messages in this thread |  | | | From | Arnd Bergmann <> | | Subject | [PATCH v2 00/13] BKL conversion in tty layer | | Date | Wed, 5 May 2010 00:33:39 +0200 |
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This is the second attempt to get the BKL out of the TTY code. I've updated the patches to be based on top of Alan's series and improved a number of things.
This series still introduces a new Big TTY Mutex that is based on the earlier implementation of the Big Kernel Semaphore, but comes with a number of changes:
- based on the mutex code instead of a semaphore, so we can use all the mutex debugging. - no autorelease on sleep, which is what most of the series is about. - limited to one subsystem only. - ability to annotate nested locking so we can eventually turn it into a non-recursive mutex, once all the recursive users stay around.
The first eight patches convert all the code using the BKL in the TTY layer and related drivers to the new interface, and patch 9/13 then adds the real mutex implementation as an experimental configuration option.
When that option is disabled, the behaviour should be basically unchanged regarding serialization against other subsystems using the BKL.
The final four patches are new and do some real cleanup, intended to improve the TTY locking towards moving the BTM out. These are not required for the big picture of the BKL removal, nothing else depends on this. I'd still like to hear from Alan if he thinks this part is useful for his work on the problem or if we should just leave it out.
Arnd Bergmann (13): tty: replace BKL with a new tty_lock tty: make atomic_write_lock release tty_lock tty: make tty_port->mutex nest under tty_lock tty: make termios mutex nest under tty_lock tty: make ldisc_mutex nest under tty_lock tty: never hold BTM while getting tty_mutex tty: give up BTM in acquire_console_sem tty: release tty lock when blocking tty: implement BTM as mutex instead of BKL tty: untangle locking of wait_until_sent tty: remove tty_lock_nested tty: remove release_tty_lock/reacquire_tty_lock tty: turn ldisc_mutex into a regular mutex
drivers/char/Makefile | 1 + drivers/char/amiserial.c | 18 +++--- drivers/char/briq_panel.c | 6 +- drivers/char/cyclades.c | 4 +- drivers/char/generic_serial.c | 2 +- drivers/char/hvc_console.c | 2 +- drivers/char/hvcs.c | 2 +- drivers/char/ip2/ip2main.c | 20 +++++- drivers/char/isicom.c | 4 +- drivers/char/istallion.c | 16 +++-- drivers/char/moxa.c | 6 +- drivers/char/mxser.c | 10 ++-- drivers/char/n_hdlc.c | 16 ++-- drivers/char/n_r3964.c | 10 ++-- drivers/char/pty.c | 26 +++---- drivers/char/riscom8.c | 4 +- drivers/char/rocket.c | 6 +- drivers/char/selection.c | 4 +- drivers/char/serial167.c | 10 ++-- drivers/char/specialix.c | 6 +- drivers/char/stallion.c | 10 ++- drivers/char/sx.c | 12 ++-- drivers/char/synclink.c | 8 +- drivers/char/synclink_gt.c | 8 +- drivers/char/synclinkmp.c | 10 ++-- drivers/char/tty_buffer.c | 6 ++- drivers/char/tty_io.c | 146 ++++++++++++++++++++++----------------- drivers/char/tty_ioctl.c | 73 ++++++++++++++----- drivers/char/tty_ldisc.c | 56 ++++++++++----- drivers/char/tty_mutex.c | 50 +++++++++++++ drivers/char/tty_port.c | 8 +- drivers/char/vc_screen.c | 4 +- drivers/char/vt_ioctl.c | 12 ++-- drivers/isdn/i4l/isdn_common.c | 20 +++--- drivers/isdn/i4l/isdn_tty.c | 10 ++-- drivers/mmc/card/sdio_uart.c | 2 +- drivers/net/irda/irtty-sir.c | 5 +- drivers/serial/68328serial.c | 2 +- drivers/serial/68360serial.c | 5 +- drivers/serial/crisv10.c | 17 +++-- drivers/serial/pmac_zilog.c | 4 +- drivers/serial/serial_core.c | 43 +++++------ drivers/staging/strip/strip.c | 2 +- drivers/usb/class/cdc-acm.c | 2 +- drivers/usb/serial/opticon.c | 2 +- drivers/usb/serial/usb-serial.c | 18 +++--- drivers/video/console/vgacon.c | 4 +- include/linux/init_task.h | 1 + include/linux/sched.h | 1 + include/linux/tty.h | 145 ++++++++++++++++++++++++++++++++++++++ kernel/fork.c | 1 + kernel/printk.c | 14 ++++- lib/Kconfig.debug | 10 +++ net/irda/ircomm/ircomm_tty.c | 2 +- 54 files changed, 599 insertions(+), 287 deletions(-) create mode 100644 drivers/char/tty_mutex.c
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