tdsigwakeup() increases the priority of the low-priority threads, to
give them a chance to be terminated timely. Also, kernel allows user
to signal kernel processes. The combined effect is that signalling
idle process bump a priority of the selected delivery thread, which
starts eating CPU.
Check for the delivery thread be an idle thread and do not raise its
priority then.
The signal delivery to the kernel threads must be opt-in feature.
Kernel thread should explicitely declare the ability to handle signals
directed to it. E.g., nfsd threads check for signal as an indication
of exit request.
Most threads do not handle signals at all, and queuing the signal to
them causes odd side-effects. Most innocent consequence is the memory
leak due to queued ksiginfo, which is never deleted from the sigqueue.
Code to prevent even queuing signals to the kernel threads is trivial,
but it requires careful examination of each call to kproc/kthread
creation to decide should the signalling be allowed. The commit is a
stop-gap measure which fixes the immediate case for now.
PR: 200493
Reported and tested by: trasz
Discussed with: trasz, emaste
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Previously format string traversal could happen while the string itself was
being modified.
Use allproc_lock as coredumping is a rare operation and as such we don't
have to create a dedicated lock.
Submitted by: Tiwei Bie <btw mail.ustc.edu.cn>
Reviewed by: kib
X-Additional: JuniorJobs project
in kern_gzio.c. The old gzio interface was somewhat inflexible and has not
worked properly since r272535: currently, the gzio functions are called with
a range lock held on the output vnode, but kern_gzio.c does not pass the
IO_RANGELOCKED flag to vn_rdwr() calls, resulting in deadlock when vn_rdwr()
attempts to reacquire the range lock. Moreover, the new gzio interface can
be used to implement kernel core compression.
This change also modifies the kernel configuration options needed to enable
userland core dump compression support: gzio is now an option rather than a
device, and the COMPRESS_USER_CORES option is removed. Core dump compression
is enabled using the kern.compress_user_cores sysctl/tunable.
Differential Revision: https://reviews.freebsd.org/D1832
Reviewed by: rpaulo
Discussed with: kib
This change implements a notification (via devctl) to userland when
the kernel produces coredumps after a process has crashed.
devd can then run a specific command to produce a human readable crash
report. The command is most usually a helper that runs gdb/lldb
commands on the file/coredump pair. It's possible to use this
functionality for implementing automatic generation of crash reports.
devd(8) will be notified of the full path of the binary that crashed and
the full path of the coredump file.
attachment to the process. Note that the command is not intended to
be a security measure, rather it is an obfuscation feature,
implemented for parity with other operating systems.
Discussed with: jilles, rwatson
Man page fixes by: rwatson
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
== SIG_DFL or SIG_IGN. Sloppy code does not fully initialize struct
sigaction for such cases, and being too demanding in the case of
default handler does not catch anything.
Reported and tested by: Alex Tutubalin <lexa@lexa.ru>
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
the created file name was cached. Use the flag for core dumps.
Requested by: rpaulo
Tested by: pho (previous version)
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
feature is to quisce the system before suspend.
Stop is implemented by reusing the thread_single(9) with the special
mode SINGLE_ALLPROC. SINGLE_ALLPROC differs from the existing
single-threading modes by allowing (requiring) caller to operate on
other process. Interruptible sleeps for !TDF_SBDRY threads are
suspended like SIGSTOP does it, instead of aborting the sleep, like
SINGLE_NO_EXIT, to avoid spurious EINTRs on resume.
Provide debugging sysctl debug.stop_all_proc, which causes total stop
and suspends syncer, while waiting for variable reset for resume. It
is used for debugging; should be removed after the real use of the
interface is added.
In collaboration with: pho
Discussed with: avg
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
method needs pre-reset state of the ps_siginfo to correctly construct
signal frame.
Move sigdflt() call after the sv_sendsig() invocation in postsig().
Simultaneously extract common code from trapsignal() and postsig()
into new helper postsig_done().
Submitted by: rea
MFC after: 1 week
- Do not dump into system files.
- Do not acquire write reference to the mount point where img.core is
written, in the coredump(). The vn_rdwr() calls from ELF imgact
request the write ref from vn_rdwr(). Recursive acqusition of the
write ref deadlocks with the unmount.
- Instead, take the range lock for the whole core file. This prevents
parallel dumping from two processes executing the same image,
converting the useless interleaved dump into sequential dumping,
with second core overwriting the first.
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
pre-r270321. Namely, the flags are preserved for SIG_DFL and SIG_IGN
dispositions.
Requested and reviewed by: jilles
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
ignored or default, are not leaking. Apparently, there exists code
which relies on SA_SIGINFO not reported for SIG_DFL or SIG_IGN.
In kern_sigaction, ignore flags when resetting. Encapsulate the flag
and disposition testing into helper sigact_flag_test().
On exec, and when delivering signal with SA_RESETHAND flag set,
signals are reset automatically. Use new helper sigdflt(), which
removes duplicated code and corrects all flag bits for the signal.
For proc0, set sigintr bit for all ignored signals. Ignored signals
are consumed in tdsendsignal() and not delivered to the victim thread
at all.
Reported and tested by: royger
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
It is used only during execve (i.e. singlethreaded), so there is no fear
of returning 'not shared' which soon becomes 'shared'.
While here reorganize the code a little to avoid proc lock/unlock in
shared case.
MFC after: 1 week
These changes prevent sysctl(8) from returning proper output,
such as:
1) no output from sysctl(8)
2) erroneously returning ENOMEM with tools like truss(1)
or uname(1)
truss: can not get etype: Cannot allocate memory
there is an environment variable which shall initialize the SYSCTL
during early boot. This works for all SYSCTL types both statically and
dynamically created ones, except for the SYSCTL NODE type and SYSCTLs
which belong to VNETs. A new flag, CTLFLAG_NOFETCH, has been added to
be used in the case a tunable sysctl has a custom initialisation
function allowing the sysctl to still be marked as a tunable. The
kernel SYSCTL API is mostly the same, with a few exceptions for some
special operations like iterating childrens of a static/extern SYSCTL
node. This operation should probably be made into a factored out
common macro, hence some device drivers use this. The reason for
changing the SYSCTL API was the need for a SYSCTL parent OID pointer
and not only the SYSCTL parent OID list pointer in order to quickly
generate the sysctl path. The motivation behind this patch is to avoid
parameter loading cludges inside the OFED driver subsystem. Instead of
adding special code to the OFED driver subsystem to post-load tunables
into dynamically created sysctls, we generalize this in the kernel.
Other changes:
- Corrected a possibly incorrect sysctl name from "hw.cbb.intr_mask"
to "hw.pcic.intr_mask".
- Removed redundant TUNABLE statements throughout the kernel.
- Some minor code rewrites in connection to removing not needed
TUNABLE statements.
- Added a missing SYSCTL_DECL().
- Wrapped two very long lines.
- Avoid malloc()/free() inside sysctl string handling, in case it is
called to initialize a sysctl from a tunable, hence malloc()/free() is
not ready when sysctls from the sysctl dataset are registered.
- Bumped FreeBSD version to indicate SYSCTL API change.
MFC after: 2 weeks
Sponsored by: Mellanox Technologies
further refinement is required as some device drivers intended to be
portable over FreeBSD versions rely on __FreeBSD_version to decide whether
to include capability.h.
MFC after: 3 weeks
requires process descriptors to work and having PROCDESC in GENERIC
seems not enough, especially that we hope to have more and more consumers
in the base.
MFC after: 3 days
In its stead use the Solaris / illumos approach of emulating '-' (dash)
in probe names with '__' (two consecutive underscores).
Reviewed by: markj
MFC after: 3 weeks
option, unbreak the lock tracing release semantic by embedding
calls to LOCKSTAT_PROFILE_RELEASE_LOCK() direclty in the inlined
version of the releasing functions for mutex, rwlock and sxlock.
Failing to do so skips the lockstat_probe_func invokation for
unlocking.
- As part of the LOCKSTAT support is inlined in mutex operation, for
kernel compiled without lock debugging options, potentially every
consumer must be compiled including opt_kdtrace.h.
Fix this by moving KDTRACE_HOOKS into opt_global.h and remove the
dependency by opt_kdtrace.h for all files, as now only KDTRACE_FRAMES
is linked there and it is only used as a compile-time stub [0].
[0] immediately shows some new bug as DTRACE-derived support for debug
in sfxge is broken and it was never really tested. As it was not
including correctly opt_kdtrace.h before it was never enabled so it
was kept broken for a while. Fix this by using a protection stub,
leaving sfxge driver authors the responsibility for fixing it
appropriately [1].
Sponsored by: EMC / Isilon storage division
Discussed with: rstone
[0] Reported by: rstone
[1] Discussed with: philip
Per POSIX, si_status should contain the value passed to exit() for
si_code==CLD_EXITED and the signal number for other si_code. This was
incorrect for CLD_EXITED and CLD_DUMPED.
This is still not fully POSIX-compliant (Austin group issue #594 says that
the full value passed to exit() shall be returned via si_status, not just
the low 8 bits) but is sufficient for a si_status-related test in libnih
(upstart, Debian/kFreeBSD).
PR: kern/184002
Reported by: Dmitrijs Ledkovs
Tested by: Dmitrijs Ledkovs
in the future in a backward compatible (API and ABI) way.
The cap_rights_t represents capability rights. We used to use one bit to
represent one right, but we are running out of spare bits. Currently the new
structure provides place for 114 rights (so 50 more than the previous
cap_rights_t), but it is possible to grow the structure to hold at least 285
rights, although we can make it even larger if 285 rights won't be enough.
The structure definition looks like this:
struct cap_rights {
uint64_t cr_rights[CAP_RIGHTS_VERSION + 2];
};
The initial CAP_RIGHTS_VERSION is 0.
The top two bits in the first element of the cr_rights[] array contain total
number of elements in the array - 2. This means if those two bits are equal to
0, we have 2 array elements.
The top two bits in all remaining array elements should be 0.
The next five bits in all array elements contain array index. Only one bit is
used and bit position in this five-bits range defines array index. This means
there can be at most five array elements in the future.
To define new right the CAPRIGHT() macro must be used. The macro takes two
arguments - an array index and a bit to set, eg.
#define CAP_PDKILL CAPRIGHT(1, 0x0000000000000800ULL)
We still support aliases that combine few rights, but the rights have to belong
to the same array element, eg:
#define CAP_LOOKUP CAPRIGHT(0, 0x0000000000000400ULL)
#define CAP_FCHMOD CAPRIGHT(0, 0x0000000000002000ULL)
#define CAP_FCHMODAT (CAP_FCHMOD | CAP_LOOKUP)
There is new API to manage the new cap_rights_t structure:
cap_rights_t *cap_rights_init(cap_rights_t *rights, ...);
void cap_rights_set(cap_rights_t *rights, ...);
void cap_rights_clear(cap_rights_t *rights, ...);
bool cap_rights_is_set(const cap_rights_t *rights, ...);
bool cap_rights_is_valid(const cap_rights_t *rights);
void cap_rights_merge(cap_rights_t *dst, const cap_rights_t *src);
void cap_rights_remove(cap_rights_t *dst, const cap_rights_t *src);
bool cap_rights_contains(const cap_rights_t *big, const cap_rights_t *little);
Capability rights to the cap_rights_init(), cap_rights_set(),
cap_rights_clear() and cap_rights_is_set() functions are provided by
separating them with commas, eg:
cap_rights_t rights;
cap_rights_init(&rights, CAP_READ, CAP_WRITE, CAP_FSTAT);
There is no need to terminate the list of rights, as those functions are
actually macros that take care of the termination, eg:
#define cap_rights_set(rights, ...) \
__cap_rights_set((rights), __VA_ARGS__, 0ULL)
void __cap_rights_set(cap_rights_t *rights, ...);
Thanks to using one bit as an array index we can assert in those functions that
there are no two rights belonging to different array elements provided
together. For example this is illegal and will be detected, because CAP_LOOKUP
belongs to element 0 and CAP_PDKILL to element 1:
cap_rights_init(&rights, CAP_LOOKUP | CAP_PDKILL);
Providing several rights that belongs to the same array's element this way is
correct, but is not advised. It should only be used for aliases definition.
This commit also breaks compatibility with some existing Capsicum system calls,
but I see no other way to do that. This should be fine as Capsicum is still
experimental and this change is not going to 9.x.
Sponsored by: The FreeBSD Foundation
using SDT_PROBE_ARGTYPE(). This will make it easy to extend the SDT(9) API
to allow probes with dynamically-translated types.
There is no functional change.
MFC after: 2 weeks
calls to toggle TDF_SBDRY rather than passing PBDRY to individual sleep
calls.
- Remove the stop_allowed parameters from cursig() and issignal().
issignal() checks TDF_SBDRY directly.
- Remove the PBDRY and SLEEPQ_STOP_ON_BDRY flags.
changes in r246417 were incomplete as they did not add explicit calls to
sigdeferstop() around all the places that previously passed SBDRY to
_sleep(). In addition, nfs_getcacheblk() could trigger a write RPC from
getblk() resulting in sigdeferstop() recursing. Rather than manually
deferring stop signals in specific places, change the VFS_*() and VOP_*()
methods to defer stop signals for filesystems which request this behavior
via a new VFCF_SBDRY flag. Note that this has to be a VFC flag rather than
a MNTK flag so that it works properly with VFS_MOUNT() when the mount is
not yet fully constructed. For now, only the NFS clients are set this new
flag in VFS_SET().
A few other related changes:
- Add an assertion to ensure that TDF_SBDRY doesn't leak to userland.
- When a lookup request uses VOP_READLINK() to follow a symlink, mark
the request as being on behalf of the thread performing the lookup
(cnp_thread) rather than using a NULL thread pointer. This causes
NFS to properly handle signals during this VOP on an interruptible
mount.
PR: kern/176179
Reported by: Russell Cattelan (sigdeferstop() recursion)
Reviewed by: kib
MFC after: 1 month
until child performs exec(). The behaviour is reasonable when a
debugger is the real parent, because the parent is stopped until
exec(), and sending a debugging event to the debugger would deadlock
both parent and child.
On the other hand, when debugger is not the parent of the vforked
child, not sending debugging signals makes it impossible to debug
across vfork.
Fix the issue by declining generating debug signals only when vfork()
was done and child called ptrace(PT_TRACEME). Set a new process flag
P_PPTRACE from the attach code for PT_TRACEME, if P_PPWAIT flag is
set, which indicates that the process was created with vfork() and
still did not execed. Check P_PPTRACE from issignal(), instead of
refusing the trace outright for the P_PPWAIT case. The scope of
P_PPTRACE is exactly contained in the scope of P_PPWAIT.
Found and tested by: zont
Reviewed by: pluknet
MFC after: 2 weeks
195702, 195703, and 195821 prevented a thread from suspending while holding
locks inside of NFS by forcing the thread to fail sleeps with EINTR or
ERESTART but defer the thread suspension to the user boundary. However,
this had the effect that stopping a process during an NFS request could
abort the request and trigger EINTR errors that were visible to userland
processes (previously the thread would have suspended and completed the
request once it was resumed).
This change instead effectively masks stop signals while in the NFS client.
It uses the existing TDF_SBDRY flag to effect this since SIGSTOP cannot
be masked directly. Also, instead of setting PBDRY on individual sleeps,
the NFS client now sets the TDF_SBDRY flag around each NFS request and
stop signals are masked for all sleeps during that region (the previous
change missed sleeps in lockmgr locks). The end result is that stop
signals sent to threads performing an NFS request are completely
ignored until after the NFS request has finished processing and the
thread prepares to return to userland. This restores the behavior of
stop signals being transparent to userland processes while still
preventing threads from suspending while holding NFS locks.
Reviewed by: kib
MFC after: 1 month
only returns name, but also vnode of corefile to use.
This simplifies the code and closes few races, especially in %I handling.
Reviewed by: kib
Obtained from: WHEEL Systems
