lwn.git/drivers/tty/vt/vt.c, branch v3.10.3

tty/vt: Fix vc_deallocate() lock order

2013-05-20T19:15:59+00:00

Now that the tty port owns the flip buffers and i/o is allowed from the driver even when no tty is attached, the destruction of the tty port (and the flip buffers) must ensure that no outstanding work is pending. Unfortunately, this creates a lock order problem with the console_lock (see attached lockdep report [1] below). For single console deallocation, drop the console_lock prior to port destruction. When multiple console deallocation, defer port destruction until the consoles have been deallocated. tty_port_destroy() is not required if the port has not been used; remove from vc_allocate() failure path. [1] lockdep report from Dave Jones ====================================================== [ INFO: possible circular locking dependency detected ] 3.9.0+ #16 Not tainted ------------------------------------------------------- (agetty)/26163 is trying to acquire lock: blocked: ((&buf->work)){+.+...}, instance: ffff88011c8b0020, at: [] flush_work+0x5/0x2e0 but task is already holding lock: blocked: (console_lock){+.+.+.}, instance: ffffffff81c2fde0, at: [] vt_ioctl+0xb61/0x1230 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (console_lock){+.+.+.}: [] lock_acquire+0xa4/0x210 [] console_lock+0x77/0x80 [] con_flush_chars+0x2d/0x50 [] n_tty_receive_buf+0x122/0x14d0 [] flush_to_ldisc+0x119/0x170 [] process_one_work+0x211/0x700 [] worker_thread+0x11b/0x3a0 [] kthread+0xed/0x100 [] ret_from_fork+0x7c/0xb0 -> #0 ((&buf->work)){+.+...}: [] __lock_acquire+0x193a/0x1c00 [] lock_acquire+0xa4/0x210 [] flush_work+0x4e/0x2e0 [] __cancel_work_timer+0x95/0x130 [] cancel_work_sync+0x10/0x20 [] tty_port_destroy+0x12/0x20 [] vc_deallocate+0xf8/0x110 [] vt_ioctl+0xb6c/0x1230 [] tty_ioctl+0x285/0xd50 [] do_vfs_ioctl+0x305/0x530 [] sys_ioctl+0x81/0xa0 [] system_call_fastpath+0x16/0x1b other info that might help us debug this: [ 6760.076175] Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(console_lock); lock((&buf->work)); lock(console_lock); lock((&buf->work)); *** DEADLOCK *** 1 lock on stack by (agetty)/26163: #0: blocked: (console_lock){+.+.+.}, instance: ffffffff81c2fde0, at: [] vt_ioctl+0xb61/0x1230 stack backtrace: Pid: 26163, comm: (agetty) Not tainted 3.9.0+ #16 Call Trace: [] print_circular_bug+0x200/0x20e [] __lock_acquire+0x193a/0x1c00 [] ? sched_clock+0x9/0x10 [] ? sched_clock+0x9/0x10 [] ? native_sched_clock+0x20/0x80 [] lock_acquire+0xa4/0x210 [] ? flush_work+0x5/0x2e0 [] flush_work+0x4e/0x2e0 [] ? flush_work+0x5/0x2e0 [] ? mark_held_locks+0xbb/0x140 [] ? __free_pages_ok.part.57+0x93/0xc0 [] ? mark_held_locks+0xbb/0x140 [] ? __cancel_work_timer+0x82/0x130 [] __cancel_work_timer+0x95/0x130 [] cancel_work_sync+0x10/0x20 [] tty_port_destroy+0x12/0x20 [] vc_deallocate+0xf8/0x110 [] vt_ioctl+0xb6c/0x1230 [] ? lock_release_holdtime.part.30+0xa1/0x170 [] tty_ioctl+0x285/0xd50 [] ? inode_has_perm.isra.46.constprop.61+0x56/0x80 [] do_vfs_ioctl+0x305/0x530 [] ? selinux_file_ioctl+0x5b/0x110 [] sys_ioctl+0x81/0xa0 [] system_call_fastpath+0x16/0x1b Cc: Dave Jones Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux

2013-02-26T00:46:44+00:00

Pull drm merge from Dave Airlie: "Highlights: - TI LCD controller KMS driver - TI OMAP KMS driver merged from staging - drop gma500 stub driver - the fbcon locking fixes - the vgacon dirty like zebra fix. - open firmware videomode and hdmi common code helpers - major locking rework for kms object handling - pageflip/cursor won't block on polling anymore! - fbcon helper and prime helper cleanups - i915: all over the map, haswell power well enhancements, valleyview macro horrors cleaned up, killing lots of legacy GTT code, - radeon: CS ioctl unification, deprecated UMS support, gpu reset rework, VM fixes - nouveau: reworked thermal code, external dp/tmds encoder support (anx9805), fences sleep instead of polling, - exynos: all over the driver fixes." Lovely conflict in radeon/evergreen_cs.c between commit de0babd60d8d ("drm/radeon: enforce use of radeon_get_ib_value when reading user cmd") and the new changes that modified that evergreen_dma_cs_parse() function. * 'drm-next' of git://people.freedesktop.org/~airlied/linux: (508 commits) drm/tilcdc: only build on arm drm/i915: Revert hdmi HDP pin checks drm/tegra: Add list of framebuffers to debugfs drm/tegra: Fix color expansion drm/tegra: Split DC_CMD_STATE_CONTROL register write drm/tegra: Implement page-flipping support drm/tegra: Implement VBLANK support drm/tegra: Implement .mode_set_base() drm/tegra: Add plane support drm/tegra: Remove bogus tegra_framebuffer structure drm: Add consistency check for page-flipping drm/radeon: Use generic HDMI infoframe helpers drm/tegra: Use generic HDMI infoframe helpers drm: Add EDID helper documentation drm: Add HDMI infoframe helpers video: Add generic HDMI infoframe helpers drm: Add some missing forward declarations drm: Move mode tables to drm_edid.c drm: Remove duplicate drm_mode_cea_vic() gma500: Fix n, m1 and m2 clock limits for sdvo and lvds ...

tty vt: fix character insertion overflow

2013-02-25T01:29:49+00:00

Commit 81732c3b2fed ("tty vt: Fix line garbage in virtual console on command line edition") broke insert_char() in multiple ways. Then commit b1a925f44a3a ("tty vt: Fix a regression in command line edition") partially fixed it. However, the buffer being moved is still too large and overflowing beyond the end of the current line, corrupting existing characters on the next line. Example test case: echo -e "abc\nde\x1b[A\x1b[4h \x1b[4l\x1b[B" Expected result: ab c de Current result: ab c e Needless to say that this is very annoying when inserting words in the middle of paragraphs with certain text editors. Signed-off-by: Nicolas Pitre Cc: Jean-François Moine Cc: Greg Kroah-Hartman Cc: Signed-off-by: Linus Torvalds

Merge branch 'console-fixes' into drm-next

2013-02-08T02:13:43+00:00

(not the fbcon maintainer pull 2) fix bug in vgacon on bootup and fbcon losing fonts on startup. * console-fixes: (50 commits) fbcon: don't lose the console font across generic->chip driver switch vgacon/vt: clear buffer attributes when we load a 512 character font (v2)

fb: Yet another band-aid for fixing lockdep mess

2013-02-08T02:02:41+00:00

I've still got lockdep warnings even after Alan's patch, and it seems that yet more band aids are required to paper over similar paths for unbind_con_driver() and unregister_con_driver(). After this hack, lockdep warnings are finally gone. Signed-off-by: Takashi Iwai Cc: Alan Cox Cc: Florian Tobias Schandinat Cc: Jiri Kosina Cc: stable Tested-by: Sedat Dilek Signed-off-by: Andrew Morton Signed-off-by: Dave Airlie

fb: rework locking to fix lock ordering on takeover

2013-02-08T02:02:40+00:00

Adjust the console layer to allow a take over call where the caller already holds the locks. Make the fb layer lock in order. This is partly a band aid, the fb layer is terminally confused about the locking rules it uses for its notifiers it seems. [akpm@linux-foundation.org: remove stray non-ascii char, tidy comment] [akpm@linux-foundation.org: export do_take_over_console()] [airlied: cleanup another non-ascii char] Signed-off-by: Alan Cox Cc: Florian Tobias Schandinat Cc: Stephen Rothwell Cc: Jiri Kosina Cc: stable Tested-by: Sedat Dilek Reviewed-by: Daniel Vetter Signed-off-by: Andrew Morton Signed-off-by: Dave Airlie

vgacon/vt: clear buffer attributes when we load a 512 character font (v2)

2013-02-07T02:37:03+00:00

When we switch from 256->512 byte font rendering mode, it means the current contents of the screen is being reinterpreted. The bit that holds the high bit of the 9-bit font, may have been previously set, and thus the new font misrenders. The problem case we see is grub2 writes spaces with the bit set, so it ends up with data like 0x820, which gets reinterpreted into 0x120 char which the font translates into G with a circumflex. This flashes up on screen at boot and is quite ugly. A current side effect of this patch though is that any rendering on the screen changes color to a slightly darker color, but at least the screen no longer corrupts. v2: as suggested by hpa, always clear the attribute space, whether we are are going to or from 512 chars. Cc: stable@vger.kernel.org Signed-off-by: Dave Airlie

TTY: switch tty_schedule_flip

2013-01-16T06:43:15+00:00

Now, we start converting tty buffer functions to actually use tty_port. This will allow us to get rid of the need of tty in many call sites. Only tty_port will needed and hence no more tty_port_tty_get in those paths. This is the last one: tty_schedule_flip Signed-off-by: Jiri Slaby Signed-off-by: Greg Kroah-Hartman

TTY: switch tty_insert_flip_char

2013-01-16T06:21:36+00:00

Now, we start converting tty buffer functions to actually use tty_port. This will allow us to get rid of the need of tty in many call sites. Only tty_port will needed and hence no more tty_port_tty_get in those paths. tty_insert_flip_char is the next one to proceed. This one is used all over the code, so the patch is huge. Signed-off-by: Jiri Slaby Signed-off-by: Greg Kroah-Hartman

Merge tag 'tty-3.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

2012-12-11T22:08:47+00:00

Pull TTY/Serial merge from Greg Kroah-Hartman: "Here's the big tty/serial tree set of changes for 3.8-rc1. Contained in here is a bunch more reworks of the tty port layer from Jiri and bugfixes from Alan, along with a number of other tty and serial driver updates by the various driver authors. Also, Jiri has been coerced^Wconvinced to be the co-maintainer of the TTY layer, which is much appreciated by me. All of these have been in the linux-next tree for a while. Signed-off-by: Greg Kroah-Hartman " Fixed up some trivial conflicts in the staging tree, due to the fwserial driver having come in both ways (but fixed up a bit in the serial tree), and the ioctl handling in the dgrp driver having been done slightly differently (staging tree got that one right, and removed both TIOCGSOFTCAR and TIOCSSOFTCAR). * tag 'tty-3.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (146 commits) staging: sb105x: fix potential NULL pointer dereference in mp_chars_in_buffer() staging/fwserial: Remove superfluous free staging/fwserial: Use WARN_ONCE when port table is corrupted staging/fwserial: Destruct embedded tty_port on teardown staging/fwserial: Fix build breakage when !CONFIG_BUG staging: fwserial: Add TTY-over-Firewire serial driver drivers/tty/serial/serial_core.c: clean up HIGH_BITS_OFFSET usage staging: dgrp: dgrp_tty.c: Audit the return values of get/put_user() staging: dgrp: dgrp_tty.c: Remove the TIOCSSOFTCAR ioctl handler from dgrp driver serial: ifx6x60: Add modem power off function in the platform reboot process serial: mxs-auart: unmap the scatter list before we copy the data serial: mxs-auart: disable the Receive Timeout Interrupt when DMA is enabled serial: max310x: Setup missing "can_sleep" field for GPIO tty/serial: fix ifx6x60.c declaration warning serial: samsung: add devicetree properties for non-Exynos SoCs serial: samsung: fix potential soft lockup during uart write tty: vt: Remove redundant null check before kfree. tty/8250 Add check for pci_ioremap_bar failure tty/8250 Add support for Commtech's Fastcom Async-335 and Fastcom Async-PCIe cards tty/8250 Add XR17D15x devices to the exar_handle_irq override ...