06 Nov, 2015
1 commit
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Currently, try_charge() tries to reclaim memory synchronously when the
high limit is breached; however, if the allocation doesn't have
__GFP_WAIT, synchronous reclaim is skipped. If a process performs only
speculative allocations, it can blow way past the high limit. This is
actually easily reproducible by simply doing "find /". slab/slub
allocator tries speculative allocations first, so as long as there's
memory which can be consumed without blocking, it can keep allocating
memory regardless of the high limit.This patch makes try_charge() always punt the over-high reclaim to the
return-to-userland path. If try_charge() detects that high limit is
breached, it adds the overage to current->memcg_nr_pages_over_high and
schedules execution of mem_cgroup_handle_over_high() which performs
synchronous reclaim from the return-to-userland path.As long as kernel doesn't have a run-away allocation spree, this should
provide enough protection while making kmemcg behave more consistently.
It also has the following benefits.- All over-high reclaims can use GFP_KERNEL regardless of the specific
gfp mask in use, e.g. GFP_NOFS, when the limit was breached.- It copes with prio inversion. Previously, a low-prio task with
small memory.high might perform over-high reclaim with a bunch of
locks held. If a higher prio task needed any of these locks, it
would have to wait until the low prio task finished reclaim and
released the locks. By handing over-high reclaim to the task exit
path this issue can be avoided.Signed-off-by: Tejun Heo
Acked-by: Michal Hocko
Reviewed-by: Vladimir Davydov
Acked-by: Johannes Weiner
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
06 Aug, 2014
1 commit
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These parameters are nowhere used, so we can remove them.
Signed-off-by: Richard Weinberger
18 Apr, 2014
1 commit
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Mostly scripted conversion of the smp_mb__* barriers.
Signed-off-by: Peter Zijlstra
Acked-by: Paul E. McKenney
Link: http://lkml.kernel.org/n/tip-55dhyhocezdw1dg7u19hmh1u@git.kernel.org
Cc: Linus Torvalds
Cc: linux-arch@vger.kernel.org
Signed-off-by: Ingo Molnar
23 Jul, 2012
1 commit
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layout based on Oleg's suggestion; single-linked list,
task->task_works points to the last element, forward pointer
from said last element points to head. I'd still prefer
much more regular scheme with two pointers in task_work,
but...Signed-off-by: Al Viro
24 May, 2012
4 commits
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After the previouse change key_replace_session_keyring() becomes a nop.
Remove the dummy definition in key.h and update the callers in
arch/*/kernel/signal.c.Signed-off-by: Oleg Nesterov
Acked-by: David Howells
Cc: Thomas Gleixner
Cc: Richard Kuo
Cc: Linus Torvalds
Cc: Alexander Gordeev
Cc: Chris Zankel
Cc: David Smith
Cc: "Frank Ch. Eigler"
Cc: Geert Uytterhoeven
Cc: Larry Woodman
Cc: Peter Zijlstra
Cc: Tejun Heo
Cc: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Al Viro -
Provide a simple mechanism that allows running code in the (nonatomic)
context of the arbitrary task.The caller does task_work_add(task, task_work) and this task executes
task_work->func() either from do_notify_resume() or from do_exit(). The
callback can rely on PF_EXITING to detect the latter case."struct task_work" can be embedded in another struct, still it has "void
*data" to handle the most common/simple case.This allows us to kill the ->replacement_session_keyring hack, and
potentially this can have more users.Performance-wise, this adds 2 "unlikely(!hlist_empty())" checks into
tracehook_notify_resume() and do_exit(). But at the same time we can
remove the "replacement_session_keyring != NULL" checks from
arch/*/signal.c and exit_creds().Note: task_work_add/task_work_run abuses ->pi_lock. This is only because
this lock is already used by lookup_pi_state() to synchronize with
do_exit() setting PF_EXITING. Fortunately the scope of this lock in
task_work.c is really tiny, and the code is unlikely anyway.Signed-off-by: Oleg Nesterov
Acked-by: David Howells
Cc: Thomas Gleixner
Cc: Richard Kuo
Cc: Linus Torvalds
Cc: Alexander Gordeev
Cc: Chris Zankel
Cc: David Smith
Cc: "Frank Ch. Eigler"
Cc: Geert Uytterhoeven
Cc: Larry Woodman
Cc: Peter Zijlstra
Cc: Tejun Heo
Cc: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Al Viro -
Signed-off-by: Al Viro
-
Signed-off-by: Al Viro
24 Mar, 2012
1 commit
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Another old/known problem. If the tracee is killed after it reports
syscall_entry, it starts the syscall and debugger can't control this.
This confuses the users and this creates the security problems for
ptrace jailers.Change tracehook_report_syscall_entry() to return non-zero if killed,
this instructs syscall_trace_enter() to abort the syscall.Reported-by: Chris Evans
Tested-by: Indan Zupancic
Signed-off-by: Oleg Nesterov
Cc: Denys Vlasenko
Cc: Tejun Heo
Cc: Pedro Alves
Cc: Jan Kratochvil
Cc: Steven Rostedt
Cc: Frederic Weisbecker
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
28 Jun, 2011
1 commit
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Kill tracehook_notify_death(), reimplement the logic in its caller,
exit_notify().Also, change the exec_id's check to use thread_group_leader() instead
of task_detached(), this is more clear. This logic only applies to
the exiting leader, a sub-thread must never change its exit_signal.Note: when the traced group leader exits the exit_signal-or-SIGCHLD
logic looks really strange:- we notify the tracer even if !thread_group_empty() but
do_wait(WEXITED) can't work until all threads exit- if the tracer is real_parent, it is not clear why can't
we use ->exit_signal event if !thread_group_empty()-v2: do not try to fix the 2nd oddity to avoid the subtle behavior
change mixed with reorganization, suggested by Tejun.Signed-off-by: Oleg Nesterov
Reviewed-by: Tejun Heo
23 Jun, 2011
6 commits
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tracehook.h is on the way out. Rename tracehook_tracer_task() to
ptrace_parent() and move it from tracehook.h to ptrace.h.Signed-off-by: Tejun Heo
Cc: Christoph Hellwig
Cc: John Johansen
Cc: Stephen Smalley
Signed-off-by: Oleg Nesterov -
At this point, tracehooks aren't useful to mainline kernel and mostly
just add an extra layer of obfuscation. Although they have comments,
without actual in-kernel users, it is difficult to tell what are their
assumptions and they're actually trying to achieve. To mainline
kernel, they just aren't worth keeping around.This patch kills the following clone and exec related tracehooks.
tracehook_prepare_clone()
tracehook_finish_clone()
tracehook_report_clone()
tracehook_report_clone_complete()
tracehook_unsafe_exec()The changes are mostly trivial - logic is moved to the caller and
comments are merged and adjusted appropriately.The only exception is in check_unsafe_exec() where LSM_UNSAFE_PTRACE*
are OR'd to bprm->unsafe instead of setting it, which produces the
same result as the field is always zero on entry. It also tests
p->ptrace instead of (p->ptrace & PT_PTRACED) for consistency, which
also gives the same result.This doesn't introduce any behavior change.
Signed-off-by: Tejun Heo
Cc: Christoph Hellwig
Signed-off-by: Oleg Nesterov -
At this point, tracehooks aren't useful to mainline kernel and mostly
just add an extra layer of obfuscation. Although they have comments,
without actual in-kernel users, it is difficult to tell what are their
assumptions and they're actually trying to achieve. To mainline
kernel, they just aren't worth keeping around.This patch kills the following trivial tracehooks.
* Ones testing whether task is ptraced. Replace with ->ptrace test.
tracehook_expect_breakpoints()
tracehook_consider_ignored_signal()
tracehook_consider_fatal_signal()* ptrace_event() wrappers. Call directly.
tracehook_report_exec()
tracehook_report_exit()
tracehook_report_vfork_done()* ptrace_release_task() wrapper. Call directly.
tracehook_finish_release_task()
* noop
tracehook_prepare_release_task()
tracehook_report_death()This doesn't introduce any behavior change.
Signed-off-by: Tejun Heo
Cc: Christoph Hellwig
Cc: Martin Schwidefsky
Signed-off-by: Oleg Nesterov -
Move SIGTRAP on exec(2) logic from tracehook_report_exec() to
ptrace_event(). This is part of changes to make ptrace_event()
smarter and handle ptrace event related details in one place.This doesn't introduce any behavior change.
Signed-off-by: Tejun Heo
Signed-off-by: Oleg Nesterov -
This patch implements ptrace_event_enabled() which tests whether a
given PTRACE_EVENT_* is enabled and use it to simplify ptrace_event()
and tracehook_prepare_clone().PT_EVENT_FLAG() macro is added which calculates PT_TRACE_* flag from
PTRACE_EVENT_*. This is used to define PT_TRACE_* flags and by
ptrace_event_enabled() to find the matching flag.This is used to make ptrace_event() and tracehook_prepare_clone()
simpler.* ptrace_event() callers were responsible for providing mask to test
whether the event was enabled. This patch implements
ptrace_event_enabled() and make ptrace_event() drop @mask and
determine whether the event is enabled from @event. Note that
@event is constant and this conversion doesn't add runtime overhead.All conversions except tracehook_report_clone_complete() are
trivial. tracehook_report_clone_complete() used to use 0 for @mask
(always enabled) but now tests whether the specified event is
enabled. This doesn't cause any behavior difference as it's
guaranteed that the event specified by @trace is enabled.* tracehook_prepare_clone() now only determines which event is
applicable and use ptrace_event_enabled() for enable test.This doesn't introduce any behavior change.
Signed-off-by: Tejun Heo
Signed-off-by: Oleg Nesterov -
task_ptrace(task) simply dereferences task->ptrace and isn't even used
consistently only adding confusion. Kill it and directly access
->ptrace instead.This doesn't introduce any behavior change.
Signed-off-by: Tejun Heo
Signed-off-by: Oleg Nesterov
05 Jun, 2011
1 commit
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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
Signed-off-by: Oleg Nesterov
21 May, 2011
1 commit
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* 'ptrace' of git://git.kernel.org/pub/scm/linux/kernel/git/oleg/misc: (41 commits)
signal: trivial, fix the "timespec declared inside parameter list" warning
job control: reorganize wait_task_stopped()
ptrace: fix signal->wait_chldexit usage in task_clear_group_stop_trapping()
signal: sys_sigprocmask() needs retarget_shared_pending()
signal: cleanup sys_sigprocmask()
signal: rename signandsets() to sigandnsets()
signal: do_sigtimedwait() needs retarget_shared_pending()
signal: introduce do_sigtimedwait() to factor out compat/native code
signal: sys_rt_sigtimedwait: simplify the timeout logic
signal: cleanup sys_rt_sigprocmask()
x86: signal: sys_rt_sigreturn() should use set_current_blocked()
x86: signal: handle_signal() should use set_current_blocked()
signal: sigprocmask() should do retarget_shared_pending()
signal: sigprocmask: narrow the scope of ->siglock
signal: retarget_shared_pending: optimize while_each_thread() loop
signal: retarget_shared_pending: consider shared/unblocked signals only
signal: introduce retarget_shared_pending()
ptrace: ptrace_check_attach() should not do s/STOPPED/TRACED/
signal: Turn SIGNAL_STOP_DEQUEUED into GROUP_STOP_DEQUEUED
signal: do_signal_stop: Remove the unneeded task_clear_group_stop_pending()
...
31 Mar, 2011
1 commit
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Fixes generated by 'codespell' and manually reviewed.
Signed-off-by: Lucas De Marchi
23 Mar, 2011
1 commit
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tracehook_notify_jctl() aids in determining whether and what to report
to the parent when a task is stopped or continued. The function also
adds an extra requirement that siglock may be released across it,
which is currently unused and quite difficult to satisfy in
well-defined manner.As job control and the notifications are about to receive major
overhaul, remove the tracehook and open code it. If ever necessary,
let's factor it out after the overhaul.* Oleg spotted incorrect CLD_CONTINUED/STOPPED selection when ptraced.
Fixed.Signed-off-by: Tejun Heo
Cc: Oleg Nesterov
Cc: Roland McGrath
28 Oct, 2010
1 commit
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Oleg Nesterov pointed out we have to prevent multiple-threads-inside-exec
itself and we can reuse ->cred_guard_mutex for it. Yes, concurrent
execve() has no worth.Let's move ->cred_guard_mutex from task_struct to signal_struct. It
naturally prevent multiple-threads-inside-exec.Signed-off-by: KOSAKI Motohiro
Reviewed-by: Oleg Nesterov
Acked-by: Roland McGrath
Acked-by: David Howells
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
16 Dec, 2009
1 commit
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Suggested by Roland.
Change tracehook_report_syscall_exit() to look at step flag and send the
trap signal if needed.This change affects ia64, microblaze, parisc, powerpc, sh. They pass
nonzero "step" argument to tracehook but since it was ignored the tracee
reports via ptrace_notify(), this is not right and not consistent.- PTRACE_SETSIGINFO doesn't work
- if the tracer resumes the tracee with signr != 0 the new signal
is generated rather than delivering it- If PT_TRACESYSGOOD is set the tracee reports the wrong exit_code
I don't have a powerpc machine, but I think this test-case should see the
difference:#include
#include
#include
#include
#includeint main(void)
{
int pid, status;if (!(pid = fork())) {
assert(ptrace(PTRACE_TRACEME) == 0);
kill(getpid(), SIGSTOP);getppid();
return 0;
}assert(pid == wait(&status));
assert(ptrace(PTRACE_SETOPTIONS, pid, 0, PTRACE_O_TRACESYSGOOD) == 0);assert(ptrace(PTRACE_SYSCALL, pid, 0,0) == 0);
assert(pid == wait(&status));assert(ptrace(PTRACE_SINGLESTEP, pid, 0,0) == 0);
assert(pid == wait(&status));if (status == 0x57F)
return 0;printf("kernel bug: status=%X shouldn't have 0x80\n", status);
return 1;
}Signed-off-by: Oleg Nesterov
Acked-by: Roland McGrath
Cc:
Cc: Ingo Molnar
Cc: Thomas Gleixner
Cc: "H. Peter Anvin"
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
24 Sep, 2009
1 commit
-
This changes tracehook_notify_jctl() so it's called with the siglock held,
and changes its argument and return value definition. These clean-ups
make it a better fit for what new tracing hooks need to check.Tracing needs the siglock here, held from the time TASK_STOPPED was set,
to avoid potential SIGCONT races if it wants to allow any blocking in its
tracing hooks.This also folds the finish_stop() function into its caller
do_signal_stop(). The function is short, called only once and only
unconditionally. It aids readability to fold it in.[oleg@redhat.com: do not call tracehook_notify_jctl() in TASK_STOPPED state]
[oleg@redhat.com: introduce tracehook_finish_jctl() helper]
Signed-off-by: Roland McGrath
Signed-off-by: Oleg Nesterov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
19 Jun, 2009
1 commit
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tracehook_unsafe_exec() doesn't need task_lock(), remove the old comment.
Signed-off-by: Oleg Nesterov
Acked-by: Roland McGrath
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
05 Jun, 2009
1 commit
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The "trace || CLONE_PTRACE" check in tracehook_report_clone() is not right,
- If the untraced task does clone(CLONE_PTRACE) the new child is not traced,
we must not queue SIGSTOP.- If we forked the traced task, but the tracer exits and untraces both the
forking task and the new child (after copy_process() drops tasklist_lock),
we should not queue SIGSTOP too.Change the code to check task_ptrace() != 0 instead. This is still racy, but
the race is harmless.We can race with another tracer attaching to this child, or the tracer can
exit and detach in parallel. But giwen that we didn't do wake_up_new_task()
yet, the child must have the pending SIGSTOP anyway.Signed-off-by: Oleg Nesterov
Acked-by: Roland McGrath
Cc: Christoph Hellwig
Cc: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
03 Apr, 2009
2 commits
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Now that task_detached() is exported, change tracehook_notify_death() to
use this helper, nobody else checks ->exit_signal == -1 by hand.Signed-off-by: Oleg Nesterov
Cc: "Eric W. Biederman"
Cc: "Metzger, Markus T"
Acked-by: Roland McGrath
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Container-init must behave like global-init to processes within the
container and hence it must be immune to unhandled fatal signals from
within the container (i.e SIG_DFL signals that terminate the process).But the same container-init must behave like a normal process to processes
in ancestor namespaces and so if it receives the same fatal signal from a
process in ancestor namespace, the signal must be processed.Implementing these semantics requires that send_signal() determine pid
namespace of the sender but since signals can originate from workqueues/
interrupt-handlers, determining pid namespace of sender may not always be
possible or safe.This patchset implements the design/simplified semantics suggested by
Oleg Nesterov. The simplified semantics for container-init are:- container-init must never be terminated by a signal from a
descendant process.- container-init must never be immune to SIGKILL from an ancestor
namespace (so a process in parent namespace must always be able
to terminate a descendant container).- container-init may be immune to unhandled fatal signals (like
SIGUSR1) even if they are from ancestor namespace. SIGKILL/SIGSTOP
are the only reliable signals to a container-init from ancestor
namespace.This patch:
Based on an earlier patch submitted by Oleg Nesterov and comments from
Roland McGrath (http://lkml.org/lkml/2008/11/19/258).The handler parameter is currently unused in the tracehook functions.
Besides, the tracehook functions are called with siglock held, so the
functions can check the handler if they later need to.Removing the parameter simiplifies changes to sig_ignored() in a follow-on
patch.Signed-off-by: Sukadev Bhattiprolu
Acked-by: Roland McGrath
Signed-off-by: Oleg Nesterov
Cc: "Eric W. Biederman"
Cc: Daniel Lezcano
Cc: Ingo Molnar
Cc: Thomas Gleixner
Cc: "H. Peter Anvin"
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
06 Sep, 2008
1 commit
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Fix some pasto's in comments in the new linux/tracehook.h and
asm-generic/syscall.h files.Reported-by: Wenji Huang
Signed-off-by: Roland McGrath
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
08 Aug, 2008
1 commit
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In the change in commit 09a05394fe2448a4139b014936330af23fa7ec83, I
overlooked two nits in the logic and this broke using CLONE_PTRACE
when PTRACE_O_TRACE* are not being used.A parent that is itself traced at all but not using PTRACE_O_TRACE*,
using CLONE_PTRACE would have its new child fail to be traced.A parent that is not itself traced at all that uses CLONE_PTRACE
(which should be a no-op in this case) would confuse the bookkeeping
and lead to a crash at exit time.This restores the missing checks and fixes both failure modes.
Reported-by: Eduardo Habkost
Signed-off-by: Roland McGrath
05 Aug, 2008
1 commit
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My last change to tracehook.h made it confuse the kerneldoc parser.
Move the #define's before the comment so it's happy again.Signed-off-by: Roland McGrath
Acked-by: Randy Dunlap
Signed-off-by: Linus Torvalds
02 Aug, 2008
1 commit
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My commit 2b2a1ff64afbadac842bbc58c5166962cf4f7664 introduced a regression
(sorry about that) for the odd case of exit_signal=0 (e.g. clone_flags=0).
This is not a normal use, but it's used by a case in the glibc test suite.Dying with exit_signal=0 sends no signal, but it's supposed to wake up a
parent's blocked wait*() calls (unlike the delayed_group_leader case).
This fixes tracehook_notify_death() and its caller to distinguish a
"signal 0" wakeup from the delayed_group_leader case (with no wakeup).Signed-off-by: Roland McGrath
Tested-by: Serge Hallyn
Signed-off-by: Linus Torvalds
27 Jul, 2008
9 commits
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This fixes some typos and errors in comments.
No code changes.Signed-off-by: Roland McGrath
-
This adds asm-generic/syscall.h, which documents what a real
asm-ARCH/syscall.h file should define. This is not used yet, but will
provide all the machine-dependent details of examining a user system call
about to begin, in progress, or just ended.Each arch should add an asm-ARCH/syscall.h that defines all the entry
points documented in asm-generic/syscall.h, as short inlines if possible.
This lets us write new tracing code that understands user system call
registers, without any new arch-specific work.Signed-off-by: Roland McGrath
Cc: Oleg Nesterov
Reviewed-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This adds tracehook.h inlines to enable a new arch feature in support of
user debugging/tracing. This is not used yet, but it lays the groundwork
for a debugger to be able to wrangle a task that's possibly running,
without interrupting its syscalls in progress.Each arch should define TIF_NOTIFY_RESUME, and in their entry.S code treat
it much like TIF_SIGPENDING. That is, it causes you to take the slow path
when returning to user mode, where you get the full user-mode state
accessible as for signal handling or ptrace. The arch code should check
TIF_NOTIFY_RESUME after handling TIF_SIGPENDING. When it's set, clear it
and then call tracehook_notify_resume().In future, tracing code will call set_notify_resume() when it wants to get
a callback in tracehook_notify_resume().Signed-off-by: Roland McGrath
Cc: Oleg Nesterov
Reviewed-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This defines a new hook tracehook_force_sigpending() that lets tracing
code decide to force TIF_SIGPENDING on in recalc_sigpending().This is not used yet, so it compiles away to nothing for now. It lays the
groundwork for new tracing code that can interrupt a task synthetically
without actually sending a signal.Signed-off-by: Roland McGrath
Cc: Oleg Nesterov
Reviewed-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This moves the ptrace logic in task death (exit_notify) into tracehook.h
inlines. Some code is rearranged slightly to make things nicer. There is
no change, only cleanup.There is one hook called with the tasklist_lock write-locked, as ptrace
needs. There is also a new hook called after exit_state changes and
without locks. This is a better place for tracing work to be in the
future, since it doesn't delay the whole system with locking.Signed-off-by: Roland McGrath
Cc: Oleg Nesterov
Reviewed-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This defines the tracehook_notify_jctl() hook to formalize the ptrace
effects on the job control notifications. There is no change, only
cleanup.Signed-off-by: Roland McGrath
Cc: Oleg Nesterov
Reviewed-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This defines the tracehook_get_signal() hook to allow tracing code to slip
in before normal signal dequeuing. This lays the groundwork for new
tracing features that can inject synthetic signals outside the normal
queue or control the disposition of delivered signals. The calling
convention lets tracehook_get_signal() decide both exactly what will
happen and what signal number to report in the handler/exit.Signed-off-by: Roland McGrath
Cc: Oleg Nesterov
Reviewed-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This adds standard tracehook.h inlines for arch code to call when
TIF_SYSCALL_TRACE has been set. This replaces having each arch implement
the ptrace guts for its syscall tracing support.Signed-off-by: Roland McGrath
Cc: Oleg Nesterov
Reviewed-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This defines tracehook_consider_fatal_signal() has a fine-grained hook for
deciding to skip the special cases for a fatal signal, as ptrace does.
There is no change, only cleanup.Signed-off-by: Roland McGrath
Cc: Oleg Nesterov
Reviewed-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds