do_signal_stop() implemented both normal group stop and trap for group
stop while ptraced. This approach has been enough but scheduled
changes require trap mechanism which can be used in more generic
manner and using group stop trap for generic trap site simplifies both
userland visible interface and implementation.
This patch adds a new jobctl flag - JOBCTL_TRAP_STOP. When set, it
triggers a trap site, which behaves like group stop trap, in
get_signal_to_deliver() after checking for pending signals. While
ptraced, do_signal_stop() doesn't stop itself. It initiates group
stop if requested and schedules JOBCTL_TRAP_STOP and returns. The
caller - get_signal_to_deliver() - is responsible for checking whether
TRAP_STOP is pending afterwards and handling it.
ptrace_attach() is updated to use JOBCTL_TRAP_STOP instead of
JOBCTL_STOP_PENDING and __ptrace_unlink() to clear all pending trap
bits and TRAPPING so that TRAP_STOP and future trap bits don't linger
after detach.
While at it, add proper function comment to do_signal_stop() and make
it return bool.
-v2: __ptrace_unlink() updated to clear JOBCTL_TRAP_MASK and TRAPPING
instead of JOBCTL_PENDING_MASK. This avoids accidentally
clearing JOBCTL_STOP_CONSUME. Spotted by Oleg.
-v3: do_signal_stop() updated to return %false without dropping
siglock while ptraced and TRAP_STOP check moved inside for(;;)
loop after group stop participation. This avoids unnecessary
relocking and also will help avoiding unnecessary traps by
consuming group stop before handling pending traps.
-v4: Jobctl trap handling moved into a separate function -
do_jobctl_trap().
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Remove the following three noop tracehooks in signals.c.
* tracehook_force_sigpending()
* tracehook_get_signal()
* tracehook_finish_jctl()
The code area is about to be updated and these hooks don't do anything
other than obfuscating the logic.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
ptracer->signal->wait_chldexit was used to wait for TRAPPING; however,
->wait_chldexit was already complicated with waker-side filtering
without adding TRAPPING wait on top of it. Also, it unnecessarily
made TRAPPING clearing depend on the current ptrace relationship - if
the ptracee is detached, wakeup is lost.
There is no reason to use signal->wait_chldexit here. We're just
waiting for JOBCTL_TRAPPING bit to clear and given the relatively
infrequent use of ptrace, bit_waitqueue can serve it perfectly.
This patch makes JOBCTL_TRAPPING wait use bit_waitqueue instead of
signal->wait_chldexit.
-v2: Use JOBCTL_*_BIT macros instead of ilog2() as suggested by Linus.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
task->jobctl currently hosts JOBCTL_STOP_PENDING and will host TRAP
pending bits too. Setting pending conditions on a dying task may make
the task unkillable. Currently, each setting site is responsible for
checking for the condition but with to-be-added job control traps this
becomes too fragile.
This patch adds task_set_jobctl_pending() which should be used when
setting task->jobctl bits to schedule a stop or trap. The function
performs the followings to ease setting pending bits.
* Sanity checks.
* If fatal signal is pending or PF_EXITING is set, no bit is set.
* STOP_SIGMASK is automatically cleared if new value is being set.
do_signal_stop() and ptrace_attach() are updated to use
task_set_jobctl_pending() instead of setting STOP_PENDING explicitly.
The surrounding structures around setting are changed to fit
task_set_jobctl_pending() better but there should be no userland
visible behavior difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
JOBCTL_TRAPPING indicates that ptracer is waiting for tracee to
(re)transit into TRACED. task_clear_jobctl_pending() must be called
when either tracee enters TRACED or the transition is cancelled for
some reason. The former is achieved by explicitly calling
task_clear_jobctl_pending() in ptrace_stop() and the latter by calling
it at the end of do_signal_stop().
Calling task_clear_jobctl_trapping() at the end of do_signal_stop()
limits the scope TRAPPING can be used and is fragile in that seemingly
unrelated changes to tracee's control flow can lead to stuck TRAPPING.
We already have task_clear_jobctl_pending() calls on those cancelling
events to clear JOBCTL_STOP_PENDING. Cancellations can be handled by
making those call sites use JOBCTL_PENDING_MASK instead and updating
task_clear_jobctl_pending() such that task_clear_jobctl_trapping() is
called automatically if no stop/trap is pending.
This patch makes the above changes and removes the fallback
task_clear_jobctl_trapping() call from do_signal_stop().
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
This patch introduces JOBCTL_PENDING_MASK and replaces
task_clear_jobctl_stop_pending() with task_clear_jobctl_pending()
which takes an extra @mask argument.
JOBCTL_PENDING_MASK is currently equal to JOBCTL_STOP_PENDING but
future patches will add more bits. recalc_sigpending_tsk() is updated
to use JOBCTL_PENDING_MASK instead.
task_clear_jobctl_pending() takes @mask which in subset of
JOBCTL_PENDING_MASK and clears the relevant jobctl bits. If
JOBCTL_STOP_PENDING is set, other STOP bits are cleared together. All
task_clear_jobctl_stop_pending() users are updated to call
task_clear_jobctl_pending() with JOBCTL_STOP_PENDING which is
functionally identical to task_clear_jobctl_stop_pending().
This patch doesn't cause any functional change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
In ptrace_stop(), after arch hook is done, the task state and jobctl
bits are updated while holding siglock. The ordering requirement
there is that TASK_TRACED is set before JOBCTL_TRAPPING is cleared to
prevent ptracer waiting on TRAPPING doesn't end up waking up TRACED is
actually set and sees TASK_RUNNING in wait(2).
Move set_current_state(TASK_TRACED) to the top of the block and
reorganize comments. This makes the ordering more obvious
(TASK_TRACED before other updates) and helps future updates to group
stop participation.
This patch doesn't cause any functional change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
PTRACE_INTERRUPT is going to be added which should also skip
task_is_traced() check in ptrace_check_attach(). Rename @kill to
@ignore_state and make it bool. Add function comment while at it.
This patch doesn't introduce any behavior difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
signal->group_stop currently hosts mostly group stop related flags;
however, it's gonna be used for wider purposes and the GROUP_STOP_
flag prefix becomes confusing. Rename signal->group_stop to
signal->jobctl and rename all GROUP_STOP_* flags to JOBCTL_*.
Bit position macros JOBCTL_*_BIT are defined and JOBCTL_* flags are
defined in terms of them to allow using bitops later.
While at it, reassign JOBCTL_TRAPPING to bit 22 to better accomodate
future additions.
This doesn't cause any functional change.
-v2: JOBCTL_*_BIT macros added as suggested by Linus.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Remove local variable wait_trap which determines whether to wait for
!TRAPPING or not and simply wait for it if attach was successful.
-v2: Oleg pointed out wait should happen iff attach was successful.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (40 commits)
tg3: Fix tg3_skb_error_unmap()
net: tracepoint of net_dev_xmit sees freed skb and causes panic
drivers/net/can/flexcan.c: add missing clk_put
net: dm9000: Get the chip in a known good state before enabling interrupts
drivers/net/davinci_emac.c: add missing clk_put
af-packet: Add flag to distinguish VID 0 from no-vlan.
caif: Fix race when conditionally taking rtnl lock
usbnet/cdc_ncm: add missing .reset_resume hook
vlan: fix typo in vlan_dev_hard_start_xmit()
net/ipv4: Check for mistakenly passed in non-IPv4 address
iwl4965: correctly validate temperature value
bluetooth l2cap: fix locking in l2cap_global_chan_by_psm
ath9k: fix two more bugs in tx power
cfg80211: don't drop p2p probe responses
Revert "net: fix section mismatches"
drivers/net/usb/catc.c: Fix potential deadlock in catc_ctrl_run()
sctp: stop pending timers and purge queues when peer restart asoc
drivers/net: ks8842 Fix crash on received packet when in PIO mode.
ip_options_compile: properly handle unaligned pointer
iwlagn: fix incorrect PCI subsystem id for 6150 devices
...
* 'for-linus' of git://git.kernel.dk/linux-block:
block: Use hlist_entry() for io_context.cic_list.first
cfq-iosched: Remove bogus check in queue_fail path
xen/blkback: potential null dereference in error handling
xen/blkback: don't call vbd_size() if bd_disk is NULL
block: blkdev_get() should access ->bd_disk only after success
CFQ: Fix typo and remove unnecessary semicolon
block: remove unwanted semicolons
Revert "block: Remove extra discard_alignment from hd_struct."
nbd: adjust 'max_part' according to part_shift
nbd: limit module parameters to a sane value
nbd: pass MSG_* flags to kernel_recvmsg()
block: improve the bio_add_page() and bio_add_pc_page() descriptions
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-ktest:
ktest: Ignore unset values of the minconfig in config_bisect
ktest: Fix result of rebooting the kernel
ktest: Fix off-by-one in config bisect result
* 'rmobile-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6:
ARM: mach-shmobile: add DMAC clock definitions on SH7372
ARM: arch-shmobile: support SDHI card detection on mackerel, using a GPIO
sh_mobile_meram: MERAM platform data for LCDC
* 'sh-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6:
dmaengine: shdma: fix a regression: initialise DMA channels for memcpy
dmaengine: shdma: Fix up fallout from runtime PM changes.
Revert "clocksource: sh_cmt: Runtime PM support"
Revert "clocksource: sh_tmu: Runtime PM support"
sh: Fix up asm-generic/ptrace.h fallout.
sh64: Move from P1SEG to CAC_ADDR for consistent sync.
sh64: asm/pgtable.h needs asm/mmu.h
sh: asm/tlb.h needs linux/swap.h
sh: mark DMA slave ID 0 as invalid
sh: Update shmin to reflect PIO dependency.
sh: arch/sh/kernel/process_32.c needs linux/prefetch.h.
sh: add MMCIF runtime PM support on ecovec
sh: switch ap325rxa to dynamically manage the platform camera
This reverts commit b1c43f82c5.
It was broken in so many ways, and results in random odd pty issues.
It re-introduced the buggy schedule_work() in flush_to_ldisc() that can
cause endless work-loops (see commit a5660b41af: "tty: fix endless
work loop when the buffer fills up").
It also used an "unsigned int" return value fo the ->receive_buf()
function, but then made multiple functions return a negative error code,
and didn't actually check for the error in the caller.
And it didn't actually work at all. BenH bisected down odd tty behavior
to it:
"It looks like the patch is causing some major malfunctions of the X
server for me, possibly related to PTYs. For example, cat'ing a
large file in a gnome terminal hangs the kernel for -minutes- in a
loop of what looks like flush_to_ldisc/workqueue code, (some ftrace
data in the quoted bits further down).
...
Some more data: It -looks- like what happens is that the
flush_to_ldisc work queue entry constantly re-queues itself (because
the PTY is full ?) and the workqueue thread will basically loop
forver calling it without ever scheduling, thus starving the consumer
process that could have emptied the PTY."
which is pretty much exactly the problem we fixed in a5660b41af.
Milton Miller pointed out the 'unsigned int' issue.
Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reported-by: Milton Miller <miltonm@bga.com>
Cc: Stefan Bigler <stefan.bigler@keymile.com>
Cc: Toby Gray <toby.gray@realvnc.com>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The free space fixup is currently initiated during mount after the call to
ubifs_write_master() which results in a write to PEBs; this has been observed
with the patch 'assert no fixup when writing a node' applied:
Move the free space fixup on mount to before the calls to
ubifs_recover_inl_heads() and ubifs_write_master(). This results in no
assertions with the previously mentioned patch applied.
Artem: tweaked the patch a bit
Signed-off-by: Ben Gardiner <bengardiner@nanometrics>
Reviewed-by: Matthew L. Creech <mlcreech@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
The current 'mount_ubifs()' implementation does not initialize the LPT until the
the master node is marked dirty. Move the LPT initialization to before marking
the master node dirty. This is a preparation for the next patch which will move
the free-space-fixup check to before marking the master node dirty, because we
have to fix-up the free space before doing any writes.
Artem: massaged the patch and commit message.
Signed-off-by: Ben Gardiner <bengardiner@nanometrics.ca>
Reviewed-by: Matthew L. Creech <mlcreech@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
The current free space fixup can result in some writing to the UBI volume
when the space_fixup flag is set.
To catch instances where UBIFS is writing to the NAND while the space_fixup
flag is set, add an assert to ubifs_write_node().
Artem: tweaked the patch, added similar assertion to the write buffer
write path.
Signed-off-by: Ben Gardiner <bengardiner@nanometrics.ca>
Reviewed-by: Matthew L. Creech <mlcreech@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Tejun Heo
Linus Torvalds
John W. Linville
Ben Gardiner