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* hurd: Make RPC input array parameters constSamuel Thibault2022-01-163-10/+10
| | | | | This follows mig's cf4bcc3f1435 ("Also add const qualifiers on server side")
* hurd: optimize exec cleanupSamuel Thibault2022-01-161-12/+14
| | | | | When ports are nul we do not need to request their deallocation. It is also useless to look for them in portnames.
* hurd: Fix exec() leak on proc_task2proc failureSamuel Thibault2022-01-151-2/+2
| | | | env is allocated after args, so should be freed before it.
* hurd: nuke all unknown ports on execSamuel Thibault2022-01-041-7/+39
| | | | | | | Ports which are not in the ports table or dtable will not make sense for the new program, so we can nuke them. Actually we shall, otherwise we would be leaking various ports, for instance the file_t of the executed program itself.
* hurd: Fix auth port leakSamuel Thibault2022-01-041-5/+8
| | | | | | If access() was used before exec, _hurd_id.rid_auth would cache an "effective" auth port. We do not want this to leak into the executed program.
* hurd: Implement _S_msg_get_dtableSamuel Thibault2022-01-021-4/+47
| | | | This will be needed for implementing lsof.
* Update copyright dates with scripts/update-copyrightsPaul Eggert2022-01-0188-88/+88
| | | | | | | | | | | | | | | | | | | | | | | I used these shell commands: ../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright (cd ../glibc && git commit -am"[this commit message]") and then ignored the output, which consisted lines saying "FOO: warning: copyright statement not found" for each of 7061 files FOO. I then removed trailing white space from math/tgmath.h, support/tst-support-open-dev-null-range.c, and sysdeps/x86_64/multiarch/strlen-vec.S, to work around the following obscure pre-commit check failure diagnostics from Savannah. I don't know why I run into these diagnostics whereas others evidently do not. remote: *** 912-#endif remote: *** 913: remote: *** 914- remote: *** error: lines with trailing whitespace found ... remote: *** error: sysdeps/unix/sysv/linux/statx_cp.c: trailing lines
* hurd: Fix static-PIE startupSamuel Thibault2021-12-287-31/+21
| | | | | | | | hurd initialization stages use RUN_HOOK to run various initialization functions. That is however using absolute addresses which need to be relocated, which is done later by csu. We can however easily make the linker compute relative addresses which thus don't need a relocation. The new SET_RELHOOK and RUN_RELHOOK macros implement this.
* hurd: let csu initialize tlsSamuel Thibault2021-12-281-15/+24
| | | | | | | | Since 9cec82de715b ("htl: Initialize later"), we let csu initialize pthreads. We can thus let it initialize tls later too, to better align with the generic order. Initialization however accesses ports which links/unlinks into the sigstate for unwinding. We can however easily skip that during initialization.
* hurd: Let report-wait use a weak reference to _hurd_itimer_threadSamuel Thibault2021-11-281-5/+0
| | | | libc.so.0.3 does not seem to need this defined any more.
* Remove "Contributed by" linesSiddhesh Poyarekar2021-09-031-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | We stopped adding "Contributed by" or similar lines in sources in 2012 in favour of git logs and keeping the Contributors section of the glibc manual up to date. Removing these lines makes the license header a bit more consistent across files and also removes the possibility of error in attribution when license blocks or files are copied across since the contributed-by lines don't actually reflect reality in those cases. Move all "Contributed by" and similar lines (Written by, Test by, etc.) into a new file CONTRIBUTED-BY to retain record of these contributions. These contributors are also mentioned in manual/contrib.texi, so we just maintain this additional record as a courtesy to the earlier developers. The following scripts were used to filter a list of files to edit in place and to clean up the CONTRIBUTED-BY file respectively. These were not added to the glibc sources because they're not expected to be of any use in future given that this is a one time task: https://gist.github.com/siddhesh/b5ecac94eabfd72ed2916d6d8157e7dc https://gist.github.com/siddhesh/15ea1f5e435ace9774f485030695ee02 Reviewed-by: Carlos O'Donell <carlos@redhat.com>
* hurd: Add support for AT_NO_AUTOMOUNTSamuel Thibault2021-08-101-0/+6
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* hurd: Avoid spurious warningSamuel Thibault2021-08-031-1/+1
| | | | | Compilers missing some flow analysis may think ss may be used uninitialized.
* hurd: Export _hurd_libc_proc_initSamuel Thibault2021-04-122-0/+8
| | | | | hurd's libdiskfs needs to be able to call _hurd_init + _hurd_libc_proc_init for bootstrap initialization.
* hurd: handle EINTR during critical sectionsSamuel Thibault2021-03-237-2/+37
| | | | | | | | | During critical sections, signal handling is deferred and thus RPCs return EINTR, even if SA_RESTART is set. We thus have to restart the whole critical section in that case. This also adds HURD_CRITICAL_UNLOCK in the cases where one wants to break the section in the middle.
* Update copyright dates with scripts/update-copyrightsPaul Eggert2021-01-0288-88/+88
| | | | | | | | | | | | | | | | I used these shell commands: ../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright (cd ../glibc && git commit -am"[this commit message]") and then ignored the output, which consisted lines saying "FOO: warning: copyright statement not found" for each of 6694 files FOO. I then removed trailing white space from benchtests/bench-pthread-locks.c and iconvdata/tst-iconv-big5-hkscs-to-2ucs4.c, to work around this diagnostic from Savannah: remote: *** pre-commit check failed ... remote: *** error: lines with trailing whitespace found remote: error: hook declined to update refs/heads/master
* hurd: set sigaction for signal preemptors in arch-independent fileSamuel Thibault2020-12-262-7/+18
| | | | | | Instead of having the arch-specific trampoline setup code detect whether preemption happened or not, we'd rather pass it the sigaction. In the future, this may also allow to change sa_flags from post_signal().
* Hurd: make sigstates hold a reference on thread portsRichard Braun2020-12-212-7/+29
| | | | | | | | | | | | | This change is required in order to correctly release per-thread resources. Directly reusing the threading library reference isn't possible since the sigstate is also used early in the main thread, before threading is initialized. * hurd/hurd/signal.h (_hurd_self_sigstate): Drop thread reference after calling _hurd_thread_sigstate. (_hurd_critical_section_lock): Likewise. * hurd/hurdsig.c (_hurd_thread_sigstate): Add a reference on the thread. (_hurd_sigstate_delete): Drop thread reference.
* hurd: implement SA_SIGINFO signal handlers.Jeremie Koenig2020-12-214-5/+10
| | | | | | | SA_SIGINFO is actually just another way of expressing what we were already passing over with struct sigcontext. This just introduces the SIGINFO interface and fixes the posix values when that interface is requested by the application.
* hurd: Also turn KERN_INVALID_ADDRESS to EINVALSamuel Thibault2020-12-191-0/+1
| | | | | When e.g. mmap is passed an invalid address we would return KERN_INVALID_ADDRESS, while POSIX applications would expect EINVAL.
* hurd: Add __libc_open and __libc_closeSamuel Thibault2020-12-161-0/+1
| | | | Needed by libpthread for sem_open and sem_close
* hurd: Add __lll_abstimed_wait_intrSamuel Thibault2020-12-165-1/+33
| | | | For semaphores, we need an interruptible version of low-level locks.
* hurd: make lll_* take a variable instead of a ptrSamuel Thibault2020-12-163-24/+30
| | | | | To be coherent with other ports, let's make lll_* take a variable, and rename those that keep taking a ptr into __lll_*.
* hurd: Rename LLL_INITIALIZER to LLL_LOCK_INITIALIZERSamuel Thibault2020-12-161-1/+1
| | | | To get coherent with other ports.
* htl: Add missing symbolsSamuel Thibault2020-12-031-1/+1
| | | | | hurd/hurdsig.c needs to detect whether __pthread_detach and __pthread_create are available, so they need to be exposed.
* hurd report-wait: Fix stpcpy usageSamuel Thibault2020-11-231-29/+49
| | | | | | | | We shall not overflow the size of the description parameter. This makes describe_number and describe_port behave like strpcpy (except for not filling all the end of buffer with zeroes) and _S_msg_report_wait use series of stpncpy-like call. If we were to overflow, we can now detect it and return ENOMEM.
* hurd S_msg_report_wait: Fix detecting fd portsSamuel Thibault2020-11-231-1/+1
| | | | | _hurd_init_dtable stays set to non-NULL, so we have to run through both _hurd_init_dtable and _hurd_dtable.
* hurd S_msg_report_wait: Fix reporting portsSamuel Thibault2020-11-231-1/+1
| | | | | This fixes the parameter order of MSG_EXAMINE, thus fixing the detection of e.g. fd ports for nicer output in ps WAIT output.
* hurd: Fix strcpy callsSamuel Thibault2020-11-221-3/+4
| | | | | | | strcpy cannot be used with overlapping buffer, we have to use memmove instead. strcpy also cannot be safely used when the destination buffer is smaller that the source, we need to use strncpy to truncate the source if needed.
* hurd: Fix _S_msg_get/set_env_variable prototypeSamuel Thibault2020-11-221-3/+3
| | | | | | | _S_msg_get_env_variable and _S_msg_set_env_variable are taking string_t, not char *. Fixes a warning with gcc 11.
* hurd: Remove some remnants of cthreadsSamuel Thibault2020-11-1512-61/+44
| | | | | Libc has actually been using mach's lock-internal.h mutex for a long time already.
* hurd: initialize libpthread before starting the signal threadSamuel Thibault2020-11-131-0/+6
| | | | | We cannot rely on csu calling __pthread_initialize_minimal before posixland_init, in some cases _init gets called before that.
* hurd: Make _hurd_libc_proc_init idempotentSamuel Thibault2020-11-131-11/+19
| | | | | For the cases where _init is getting called several times during startup. Better clean pointers anyway.
* hurd: Notify the proc server later during initializationSamuel Thibault2020-11-111-11/+25
| | | | | | Notifying the proc server is an involved task, and unleashes various signal handling etc. so we have to do this after e.g. ifunc relocations are completed.
* htl: Initialize laterSamuel Thibault2020-11-111-3/+0
| | | | | | | | Since htl does not actually need a stack switch, we can initialize it like nptl is, avoiding all sorts of startup issues with ifunc. More precisely, htl defines __pthread_initialize_minimal instead of the elder _cthread_init_routine. We can then drop the stack switching dances.
* hurd: Rework sbrkSamuel Thibault2020-08-051-3/+0
| | | | | | | | | | | | | | | | | | | | | | | | | Making the brk start exactly at the end of the main application binary was requiring to get it through the _end symbol, which does not work any more with recent toolchains, and actually produces in libc.so a confusing external _end symbol that produces odd results, see https://sourceware.org/bugzilla/show_bug.cgi?id=23499 Trying to do so is quite outdated anyway with the tendency for address randomization. Using _end was also allowing to include the main binary data within the RLIMIT_DATA, but this also seems outdated with dynamic library loading, and nowadays' memory consumption via malloc and mmap rather than statically-allocated data. This adds a BRK_START macro in <vm_param.h> that just tells where we want to start the brk, and thus removes the _end symbol. * sysdeps/mach/hurd/i386/vm_param.h: New file. * sysdeps/mach/hurd/brk.c: Use BRK_START as brk start instead of _end. Also ignore __data_start. * hurd/Versions: Remove _end symbol. * sysdeps/mach/hurd/i386/libc.abilist: Remove _end symbol.
* hurd: Add remaining cancelation pointsSamuel Thibault2020-06-281-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * hurd/hurdselect.c: Include <sysdep-cancel.h>. (_hurd_select): Surround call to __mach_msg with enabling async cancel. * sysdeps/mach/hurd/accept4.c: Include <sysdep-cancel.h>. (__libc_accept4): Surround call to __socket_accept with enabling async cancel, and use HURD_DPORT_USE_CANCEL instead of HURD_DPORT_USE. * sysdeps/mach/hurd/connect.c: Include <sysdep-cancel.h>. (__connect): Surround call to __file_name_lookup and __socket_connect with enabling async cancel, and use HURD_DPORT_USE_CANCEL instead of HURD_DPORT_USE. * sysdeps/mach/hurd/fdatasync.c: Include <sysdep-cancel.h>. (fdatasync): Surround call to __file_sync with enabling async cancel, and use HURD_DPORT_USE_CANCEL instead of HURD_DPORT_USE. * sysdeps/mach/hurd/fsync.c: Include <sysdep-cancel.h>. (fsync): Surround call to __file_sync with enabling async cancel, and use HURD_DPORT_USE_CANCEL instead of HURD_DPORT_USE. * sysdeps/mach/hurd/ioctl.c: Include <sysdep-cancel.h>. (__ioctl): When request is TIOCDRAIN, surround call to send_rpc with enabling async cancel, and use HURD_DPORT_USE_CANCEL instead of HURD_DPORT_USE. * sysdeps/mach/hurd/msync.c: Include <sysdep-cancel.h>. (msync): Surround call to __vm_object_sync with enabling async cancel. * sysdeps/mach/hurd/sigsuspend.c: Include <sysdep-cancel.h>. (__sigsuspend): Surround call to __mach_msg with enabling async cancel. * sysdeps/mach/hurd/sigwait.c: Include <sysdep-cancel.h>. (__sigwait): Surround wait code with enabling async cancel. * sysdeps/mach/msync.c: Include <sysdep-cancel.h>. (msync): Surround call to __vm_msync with enabling async cancel. * sysdeps/mach/sleep.c: Include <sysdep-cancel.h>. (__sleep): Surround call to __mach_msg with enabling async cancel. * sysdeps/mach/usleep.c: Include <sysdep-cancel.h>. (usleep): Surround call to __vm_msync with enabling async cancel.
* hurd: clean fd and port on thread cancelSamuel Thibault2020-06-288-4/+52
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | HURD_*PORT_USE link fd and port with a stack-stored structure, so on thread cancel we need to cleanup this. * hurd/fd-cleanup.c: New file. * hurd/port-cleanup.c (_hurd_port_use_cleanup): New function. * hurd/Makefile (routines): Add fd-cleanup. * sysdeps/hurd/include/hurd.h (__USEPORT_CANCEL): New macro. * sysdeps/hurd/include/hurd/fd.h (_hurd_fd_port_use_data): New structure. (_hurd_fd_port_use_cleanup): New prototype. (HURD_DPORT_USE_CANCEL, HURD_FD_PORT_USE_CANCEL): New macros. * sysdeps/hurd/include/hurd/port.h (_hurd_port_use_data): New structure. (_hurd_port_use_cleanup): New prototype. (HURD_PORT_USE_CANCEL): New macro. * hurd/hurd/fd.h (HURD_FD_PORT_USE): Also refer to HURD_FD_PORT_USE_CANCEL. * hurd/hurd.h (__USEPORT): Also refer to __USEPORT_CANCEL. * hurd/hurd/port.h (HURD_PORT_USE): Also refer to HURD_PORT_USE_CANCEL. * hurd/fd-read.c (_hurd_fd_read): Call HURD_FD_PORT_USE_CANCEL instead of HURD_FD_PORT_USE. * hurd/fd-write.c (_hurd_fd_write): Likewise. * sysdeps/mach/hurd/send.c (__send): Call HURD_DPORT_USE_CANCEL instead of HURD_DPORT_USE. * sysdeps/mach/hurd/sendmsg.c (__libc_sendmsg): Likewise. * sysdeps/mach/hurd/sendto.c (__sendto): Likewise. * sysdeps/mach/hurd/recv.c (__recv): Likewise. * sysdeps/mach/hurd/recvfrom.c (__recvfrom): Likewise. * sysdeps/mach/hurd/recvmsg.c (__libc_recvmsg): Call __USEPORT_CANCEL instead of __USEPORT, and HURD_DPORT_USE_CANCEL instead of HURD_DPORT_USE.
* hurd: Fix hang in _hurd_raise_signal from pthread_killSamuel Thibault2020-06-071-1/+5
| | | | | | | When ss is not NULL, it is assumed to be locked. * hurd/hurd-raise.c (_hurd_raise_signal): Unlock before returning an error if ss is not NULL.
* hurd: Reject raising invalid signalsSamuel Thibault2020-06-071-0/+3
| | | | | * hurd/hurd-raise.c (_hurd_raise_signal): Return EINVAL if signo <= 0 or signo >= NSI.
* Hurd: Move <hurd/sigpreempt.h> internals into wrapper headerFlorian Weimer2020-05-281-10/+0
| | | | | | | | _hurdsig_preemptors and _hurdsig_preempted_set are not ABI symbols, so do not declare them. HURD_PREEMPT_SIGNAL_P is an implementation detail, so move it as well. Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
* Hurd: Use __sigmask in favor of deprecated sigmaskFlorian Weimer2020-05-284-9/+9
| | | | | | | | | This fixes various build errors due to deprecation warnings. Fixes commit 02802fafcf6e11ea3f998f685035ffe568dfddeb ("signal: Deprecate additional legacy signal handling functions"). Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
* hurd: Fix pselect atomicitySamuel Thibault2020-05-282-10/+70
| | | | | | | | | | | | | | In case the signal arrives before the __mach_msg call, we need to catch between the sigprocmask call and the __mach_msg call. Let's just reuse the support for sigsuspend to make the signal send a message that our __mach_msg call will just receive. * hurd/hurdselect.c (_hurd_select): Add sigport and ss variables. When sigmask is not NULL, create a sigport port and register as ss->suspended. Add it to the portset. When we receive a message on it, set error to EINTR. Clean up sigport and portset appropriately. * hurd/hurdsig.c (wake_sigsuspend): Note that pselect also uses it.
* htl: Add clock variantsSamuel Thibault2020-05-261-0/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * htl/pt-join.c (__pthread_join): Move implementation to... (__pthread_join_common): ... new function. Add try, timed and clock support. (__pthread_join): Reimplement on top of __pthread_join_common. (__pthread_tryjoin_np, __pthread_timedjoin_np, __pthread_clockjoin_np): Implement on top of __pthread_join_common. (pthread_tryjoin_np, pthread_timedjoin_np, pthread_clockjoin_np): New aliases. * hurd/hurdlock.c (__lll_abstimed_wait, __lll_abstimed_xwait, __lll_abstimed_lock): Check for supported clock. * sysdeps/htl/pt-cond-timedwait.c (__pthread_cond_timedwait_internal): Add clockid parameter and support it. (__pthread_cond_timedwait): Pass -1 as clockid. (__pthread_cond_clockwait): New function. (pthread_cond_clockwait): New alias. * sysdeps/htl/pt-cond-wait.c (__pthread_cond_timedwait_internal): Update prototype. (__pthread_cond_wait): Pass -1 as clockid. * sysdeps/htl/pt-rwlock-timedrdlock.c (__pthread_rwlock_timedrdlock_internal): Add clockid parameter, and support id. (__pthread_rwlock_clockrdlock): New function. (pthread_rwlock_clockrdlock): New alias. * sysdeps/htl/pt-rwlock-rdlock.c (__pthread_rwlock_timedrdlock_internal): Update prototype. (__pthread_rwlock_rdlock): Pass -1 as clockid. * sysdeps/htl/pt-rwlock-timedwrlock.c (__pthread_rwlock_timedwrlock_internal): Add clockid parameter, and support id. (__pthread_rwlock_clockwrlock): New function. (pthread_rwlock_clockwrlock): New alias. * sysdeps/htl/pt-rwlock-wrlock.c (__pthread_rwlock_timedwrlock_internal): Update prototype. (__pthread_rwlock_wrlock): Pass -1 as clockid. * sysdeps/mach/hurd/htl/pt-mutex-timedlock.c (__pthread_mutex_timedlock): Move implementation to (__pthread_mutex_clocklock): New function with additional clockid parameter and support it. (pthread_mutex_clocklock): New alias. (__pthread_mutex_timedlock): Reimplement on top of __pthread_mutex_clocklock. * sysdeps/htl/pthread.h (pthread_tryjoin_np, pthread_timedjoin_np, pthread_clockjoin_np, pthread_mutex_clocklock, pthread_cond_clockwait, pthread_rwlock_clockrdlock, pthread_rwlock_clockwrlock): New prototypes. * sysdeps/htl/pthreadP.h (__pthread_cond_clockwait): New prototype. * htl/Versions (GLIBC_2.32): Add pthread_cond_clockwait, pthread_mutex_clocklock, pthread_rwlock_clockrdlock, pthread_rwlock_clockwrlock, pthread_tryjoin_np, pthread_timedjoin_np, pthread_clockjoin_np. * sysdeps/mach/hurd/i386/libpthread.abilist (pthread_clockjoin_np, pthread_cond_clockwait, pthread_mutex_clocklock, pthread_rwlock_clockrdlock, pthread_rwlock_clockwrlock, pthread_timedjoin_np, pthread_tryjoin_np): New functions. * nptl/tst-abstime.c, nptl/tst-join10.c, nptl/tst-join11.c, nptl/tst-join12.c, nptl/tst-join13.c, nptl/tst-join14.c, nptl/tst-join2.c, nptl/tst-join3.c, nptl/tst-join8.c, nptl/tst-join9.c, nptl/tst-mutex-errorcheck.c, nptl/tst-pthread-mutexattr.c, nptl/tst-mutex11.c, nptl/tst-mutex5.c, nptl/tst-mutex7.c, nptl/tst-mutex7robus.c, nptl/tst-mutex9.c, nptl/tst-rwlock12.c, nptl/tst-rwlock14.c: Move to sysdeps/pthread. * sysdeps/pthread/tst-mutex8.c: Move back to nptl. * nptl/Makefile (tests): Move tst-mutex5, tst-mutex7, tst-mutex7robust, tst-mutex9, tst-mutex11, tst-rwlock12, tst-rwlock14, tst-join2, tst-join3, tst-join8, tst-join9 tst-join10, tst-join11, tst-join12, tst-join13, tst-join14, tst-abstime, tst-mutex-errorcheck, tst-pthread-mutexattr to ... * sysdeps/pthread/Makefile (tests): ... here.
* hurd: Add missing sigstate members initializationSamuel Thibault2020-05-111-1/+5
| | | | | * hurd/hurdsig.c (_hurd_thread_sigstate): Initialize critical_section_lock, active_resources, cancel, and cancel_hook fields.
* hurd: Make O_TRUNC update mtime/ctimeSamuel Thibault2020-03-291-2/+11
| | | | | * hurd/lookup-retry.c (__hurd_file_name_lookup_retry): Call __file_utimens after __file_set_size.
* hurd: Add THREAD_GET/SETMEM/_NCSamuel Thibault2020-02-151-5/+6
| | | | Store them in the TCB, and use them for accessing _hurd_sigstate.
* Update copyright dates with scripts/update-copyrights.Joseph Myers2020-01-0187-87/+87
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* hurd: Global signal dispositionJeremie Koenig2019-12-297-108/+282
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds _hurd_sigstate_set_global_rcv used by libpthread to enable POSIX-confirming behavior of signals on a per-thread basis. This also provides a sigstate destructor _hurd_sigstate_delete, and a global process signal state, which needs to be locked and check when global disposition is enabled, thus the addition of _hurd_sigstate_lock _hurd_sigstate_actions _hurd_sigstate_pending _hurd_sigstate_unlock helpers. This also updates all the glibc code accordingly. This also drops support for get_int(INIT_SIGMASK), which did not make sense any more since we do not have a single signal thread any more. During fork/spawn, this also reinitializes the child global sigstate's lock. That cures an issue that would very rarely cause a deadlock in the child in fork, tries to unlock ss' critical section lock at the end of fork. This will typically (always?) be observed in /bin/sh, which is not surprising as that is the foremost caller of fork. To reproduce an intermediate state, add an endless loop if _hurd_global_sigstate is locked after __proc_dostop (cast through volatile); that is, while still being in the fork's parent process. When that triggers (use the libtool testsuite), the signal thread has already locked ss (which is _hurd_global_sigstate), and is stuck at hurdsig.c:685 in post_signal, trying to lock _hurd_siglock (which the main thread already has locked and keeps locked until after __task_create). This is the case that ss->thread == MACH_PORT_NULL, that is, a global signal. In the main thread, between __proc_dostop and __task_create is the __thread_abort call on the signal thread which would abort any current kernel operation (but leave ss locked). Later in fork, in the parent, when _hurd_siglock is unlocked in fork, the parent's signal thread can proceed and will unlock eventually the global sigstate. In the client, _hurd_siglock will likewise be unlocked, but the global sigstate never will be, as the client's signal thread has been configured to restart execution from _hurd_msgport_receive. Thus, when the child tries to unlock ss' critical section lock at the end of fork, it will first lock the global sigstate, will spin trying to lock it, which can never be successful, and we get our deadlock. Options seem to be: * Move the locking of _hurd_siglock earlier in post_signal -- but that may generally impact performance, if this locking isn't generally needed anyway? On the other hand, would it actually make sense to wait here until we are not any longer in a critical section (which is meant to disable signal delivery anyway (but not for preempted signals?))? * Clear the global sigstate in the fork's child with the rationale that we're anyway restarting the signal thread from a clean state. This has now been implemented. Why has this problem not been observed before Jérémie's patches? (Or has it? Perhaps even more rarely?) In _S_msg_sig_post, the signal is now posted to a *global receiver thread*, whereas previously it was posted to the *designated signal-receiving thread*. The latter one was in a critical section in fork, so didn't try to handle the signal until after leaving the critical section? (Not completely analyzed and verified.) Another question is what the signal is that is being received during/around the time __proc_dostop executes.
* hurd: Signal code refactoringJeremie Koenig2019-12-291-112/+160
| | | | | | | | | | | | | This should not change the current behavior, although this fixes a few minor bugs which were made apparent in the process of global signal disposition work: - Split into more functions - Scope variables more restrictively - Split out inner functions - refactor check_pending_signals - make sigsuspend POSIX-conformant. - fix uninitialized act value.
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