diff options
Diffstat (limited to 'sys/compat/linux/linux_futex.c')
| -rw-r--r-- | sys/compat/linux/linux_futex.c | 822 |
1 files changed, 822 insertions, 0 deletions
diff --git a/sys/compat/linux/linux_futex.c b/sys/compat/linux/linux_futex.c new file mode 100644 index 000000000000..d72a699cadea --- /dev/null +++ b/sys/compat/linux/linux_futex.c @@ -0,0 +1,822 @@ +/* $NetBSD: linux_futex.c,v 1.7 2006/07/24 19:01:49 manu Exp $ */ + +/*- + * Copyright (c) 2005 Emmanuel Dreyfus, all rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by Emmanuel Dreyfus + * 4. The name of the author may not be used to endorse or promote + * products derived from this software without specific prior written + * permission. + * + * THIS SOFTWARE IS PROVIDED BY THE THE AUTHOR AND CONTRIBUTORS ``AS IS'' + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, + * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR + * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS + * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); +#if 0 +__KERNEL_RCSID(1, "$NetBSD: linux_futex.c,v 1.7 2006/07/24 19:01:49 manu Exp $"); +#endif + +#include "opt_compat.h" + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/imgact.h> +#include <sys/kernel.h> +#include <sys/ktr.h> +#include <sys/lock.h> +#include <sys/malloc.h> +#include <sys/mutex.h> +#include <sys/priv.h> +#include <sys/proc.h> +#include <sys/queue.h> +#include <sys/sched.h> +#include <sys/sx.h> + +#ifdef COMPAT_LINUX32 +#include <machine/../linux32/linux.h> +#include <machine/../linux32/linux32_proto.h> +#else +#include <machine/../linux/linux.h> +#include <machine/../linux/linux_proto.h> +#endif +#include <compat/linux/linux_futex.h> +#include <compat/linux/linux_emul.h> +#include <compat/linux/linux_util.h> + +MALLOC_DEFINE(M_FUTEX, "futex", "Linux futexes"); +MALLOC_DEFINE(M_FUTEX_WP, "futex wp", "Linux futexes wp"); + +struct futex; + +struct waiting_proc { + uint32_t wp_flags; + struct futex *wp_futex; + TAILQ_ENTRY(waiting_proc) wp_list; +}; + +struct futex { + struct sx f_lck; + uint32_t *f_uaddr; + uint32_t f_refcount; + LIST_ENTRY(futex) f_list; + TAILQ_HEAD(lf_waiting_proc, waiting_proc) f_waiting_proc; +}; + +struct futex_list futex_list; + +#define FUTEX_LOCK(f) sx_xlock(&(f)->f_lck) +#define FUTEX_UNLOCK(f) sx_xunlock(&(f)->f_lck) +#define FUTEX_INIT(f) sx_init_flags(&(f)->f_lck, "ftlk", 0) +#define FUTEX_DESTROY(f) sx_destroy(&(f)->f_lck) +#define FUTEX_ASSERT_LOCKED(f) sx_assert(&(f)->f_lck, SA_XLOCKED) + +struct mtx futex_mtx; /* protects the futex list */ +#define FUTEXES_LOCK mtx_lock(&futex_mtx) +#define FUTEXES_UNLOCK mtx_unlock(&futex_mtx) + +/* flags for futex_get() */ +#define FUTEX_CREATE_WP 0x1 /* create waiting_proc */ +#define FUTEX_DONTCREATE 0x2 /* don't create futex if not exists */ +#define FUTEX_DONTEXISTS 0x4 /* return EINVAL if futex exists */ + +/* wp_flags */ +#define FUTEX_WP_REQUEUED 0x1 /* wp requeued - wp moved from wp_list + * of futex where thread sleep to wp_list + * of another futex. + */ +#define FUTEX_WP_REMOVED 0x2 /* wp is woken up and removed from futex + * wp_list to prevent double wakeup. + */ + +/* support.s */ +int futex_xchgl(int oparg, uint32_t *uaddr, int *oldval); +int futex_addl(int oparg, uint32_t *uaddr, int *oldval); +int futex_orl(int oparg, uint32_t *uaddr, int *oldval); +int futex_andl(int oparg, uint32_t *uaddr, int *oldval); +int futex_xorl(int oparg, uint32_t *uaddr, int *oldval); + +static void +futex_put(struct futex *f, struct waiting_proc *wp) +{ + + FUTEX_ASSERT_LOCKED(f); + if (wp != NULL) { + if ((wp->wp_flags & FUTEX_WP_REMOVED) == 0) + TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list); + free(wp, M_FUTEX_WP); + } + + FUTEXES_LOCK; + if (--f->f_refcount == 0) { + LIST_REMOVE(f, f_list); + FUTEXES_UNLOCK; + FUTEX_UNLOCK(f); + + LINUX_CTR2(sys_futex, "futex_put destroy uaddr %p ref %d", + f->f_uaddr, f->f_refcount); + FUTEX_DESTROY(f); + free(f, M_FUTEX); + return; + } + + LINUX_CTR2(sys_futex, "futex_put uaddr %p ref %d", + f->f_uaddr, f->f_refcount); + FUTEXES_UNLOCK; + FUTEX_UNLOCK(f); +} + +static int +futex_get0(uint32_t *uaddr, struct futex **newf, uint32_t flags) +{ + struct futex *f, *tmpf; + + *newf = tmpf = NULL; + +retry: + FUTEXES_LOCK; + LIST_FOREACH(f, &futex_list, f_list) { + if (f->f_uaddr == uaddr) { + if (tmpf != NULL) { + FUTEX_UNLOCK(tmpf); + FUTEX_DESTROY(tmpf); + free(tmpf, M_FUTEX); + } + if (flags & FUTEX_DONTEXISTS) { + FUTEXES_UNLOCK; + return (EINVAL); + } + + /* + * Increment refcount of the found futex to + * prevent it from deallocation before FUTEX_LOCK() + */ + ++f->f_refcount; + FUTEXES_UNLOCK; + + FUTEX_LOCK(f); + *newf = f; + LINUX_CTR2(sys_futex, "futex_get uaddr %p ref %d", + uaddr, f->f_refcount); + return (0); + } + } + + if (flags & FUTEX_DONTCREATE) { + FUTEXES_UNLOCK; + LINUX_CTR1(sys_futex, "futex_get uaddr %p null", uaddr); + return (0); + } + + if (tmpf == NULL) { + FUTEXES_UNLOCK; + tmpf = malloc(sizeof(*tmpf), M_FUTEX, M_WAITOK | M_ZERO); + tmpf->f_uaddr = uaddr; + tmpf->f_refcount = 1; + FUTEX_INIT(tmpf); + TAILQ_INIT(&tmpf->f_waiting_proc); + + /* + * Lock the new futex before an insert into the futex_list + * to prevent futex usage by other. + */ + FUTEX_LOCK(tmpf); + goto retry; + } + + LIST_INSERT_HEAD(&futex_list, tmpf, f_list); + FUTEXES_UNLOCK; + + LINUX_CTR2(sys_futex, "futex_get uaddr %p ref %d new", + uaddr, tmpf->f_refcount); + *newf = tmpf; + return (0); +} + +static int +futex_get(uint32_t *uaddr, struct waiting_proc **wp, struct futex **f, + uint32_t flags) +{ + int error; + + if (flags & FUTEX_CREATE_WP) { + *wp = malloc(sizeof(struct waiting_proc), M_FUTEX_WP, M_WAITOK); + (*wp)->wp_flags = 0; + } + error = futex_get0(uaddr, f, flags); + if (error) { + if (flags & FUTEX_CREATE_WP) + free(*wp, M_FUTEX_WP); + return (error); + } + if (flags & FUTEX_CREATE_WP) { + TAILQ_INSERT_HEAD(&(*f)->f_waiting_proc, *wp, wp_list); + (*wp)->wp_futex = *f; + } + + return (error); +} + +static int +futex_sleep(struct futex *f, struct waiting_proc *wp, unsigned long timeout) +{ + int error; + + FUTEX_ASSERT_LOCKED(f); + LINUX_CTR4(sys_futex, "futex_sleep enter uaddr %p wp %p timo %ld ref %d", + f->f_uaddr, wp, timeout, f->f_refcount); + error = sx_sleep(wp, &f->f_lck, PCATCH, "futex", timeout); + if (wp->wp_flags & FUTEX_WP_REQUEUED) { + KASSERT(f != wp->wp_futex, ("futex != wp_futex")); + LINUX_CTR5(sys_futex, "futex_sleep out error %d uaddr %p w" + " %p requeued uaddr %p ref %d", + error, f->f_uaddr, wp, wp->wp_futex->f_uaddr, + wp->wp_futex->f_refcount); + futex_put(f, NULL); + f = wp->wp_futex; + FUTEX_LOCK(f); + } else + LINUX_CTR3(sys_futex, "futex_sleep out error %d uaddr %p wp %p", + error, f->f_uaddr, wp); + + futex_put(f, wp); + return (error); +} + +static int +futex_wake(struct futex *f, int n) +{ + struct waiting_proc *wp, *wpt; + int count = 0; + + FUTEX_ASSERT_LOCKED(f); + TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) { + LINUX_CTR3(sys_futex, "futex_wake uaddr %p wp %p ref %d", + f->f_uaddr, wp, f->f_refcount); + wp->wp_flags |= FUTEX_WP_REMOVED; + TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list); + wakeup_one(wp); + if (++count == n) + break; + } + + return (count); +} + +static int +futex_requeue(struct futex *f, int n, struct futex *f2, int n2) +{ + struct waiting_proc *wp, *wpt; + int count = 0; + + FUTEX_ASSERT_LOCKED(f); + FUTEX_ASSERT_LOCKED(f2); + + TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) { + if (++count <= n) { + LINUX_CTR2(sys_futex, "futex_req_wake uaddr %p wp %p", + f->f_uaddr, wp); + wp->wp_flags |= FUTEX_WP_REMOVED; + TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list); + wakeup_one(wp); + } else { + LINUX_CTR3(sys_futex, "futex_requeue uaddr %p wp %p to %p", + f->f_uaddr, wp, f2->f_uaddr); + wp->wp_flags |= FUTEX_WP_REQUEUED; + /* Move wp to wp_list of f2 futex */ + TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list); + TAILQ_INSERT_HEAD(&f2->f_waiting_proc, wp, wp_list); + + /* + * Thread which sleeps on wp after waking should + * acquire f2 lock, so increment refcount of f2 to + * prevent it from premature deallocation. + */ + wp->wp_futex = f2; + FUTEXES_LOCK; + ++f2->f_refcount; + FUTEXES_UNLOCK; + if (count - n >= n2) + break; + } + } + + return (count); +} + +static int +futex_wait(struct futex *f, struct waiting_proc *wp, struct l_timespec *ts) +{ + struct l_timespec timeout = {0, 0}; + struct timeval tv = {0, 0}; + int timeout_hz; + int error; + + if (ts != NULL) { + error = copyin(ts, &timeout, sizeof(timeout)); + if (error) + return (error); + } + + tv.tv_usec = timeout.tv_sec * 1000000 + timeout.tv_nsec / 1000; + timeout_hz = tvtohz(&tv); + + if (timeout.tv_sec == 0 && timeout.tv_nsec == 0) + timeout_hz = 0; + + /* + * If the user process requests a non null timeout, + * make sure we do not turn it into an infinite + * timeout because timeout_hz gets null. + * + * We use a minimal timeout of 1/hz. Maybe it would + * make sense to just return ETIMEDOUT without sleeping. + */ + if (((timeout.tv_sec != 0) || (timeout.tv_nsec != 0)) && + (timeout_hz == 0)) + timeout_hz = 1; + + error = futex_sleep(f, wp, timeout_hz); + if (error == EWOULDBLOCK) + error = ETIMEDOUT; + + return (error); +} + +static int +futex_atomic_op(struct thread *td, int encoded_op, uint32_t *uaddr) +{ + int op = (encoded_op >> 28) & 7; + int cmp = (encoded_op >> 24) & 15; + int oparg = (encoded_op << 8) >> 20; + int cmparg = (encoded_op << 20) >> 20; + int oldval = 0, ret; + + if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) + oparg = 1 << oparg; + +#ifdef DEBUG + if (ldebug(sys_futex)) + printf("futex_atomic_op: op = %d, cmp = %d, oparg = %x, " + "cmparg = %x, uaddr = %p\n", + op, cmp, oparg, cmparg, uaddr); +#endif + /* XXX: linux verifies access here and returns EFAULT */ + + switch (op) { + case FUTEX_OP_SET: + ret = futex_xchgl(oparg, uaddr, &oldval); + break; + case FUTEX_OP_ADD: + ret = futex_addl(oparg, uaddr, &oldval); + break; + case FUTEX_OP_OR: + ret = futex_orl(oparg, uaddr, &oldval); + break; + case FUTEX_OP_ANDN: + ret = futex_andl(~oparg, uaddr, &oldval); + break; + case FUTEX_OP_XOR: + ret = futex_xorl(oparg, uaddr, &oldval); + break; + default: + ret = -ENOSYS; + break; + } + + if (ret) + return (ret); + + switch (cmp) { + case FUTEX_OP_CMP_EQ: + return (oldval == cmparg); + case FUTEX_OP_CMP_NE: + return (oldval != cmparg); + case FUTEX_OP_CMP_LT: + return (oldval < cmparg); + case FUTEX_OP_CMP_GE: + return (oldval >= cmparg); + case FUTEX_OP_CMP_LE: + return (oldval <= cmparg); + case FUTEX_OP_CMP_GT: + return (oldval > cmparg); + default: + return (-ENOSYS); + } +} + +int +linux_sys_futex(struct thread *td, struct linux_sys_futex_args *args) +{ + int op_ret, val, ret, nrwake; + struct linux_emuldata *em; + struct waiting_proc *wp; + struct futex *f, *f2; + int error = 0; + + /* + * Our implementation provides only privates futexes. Most of the apps + * should use private futexes but don't claim so. Therefore we treat + * all futexes as private by clearing the FUTEX_PRIVATE_FLAG. It works + * in most cases (ie. when futexes are not shared on file descriptor + * or between different processes.). + */ + args->op = (args->op & ~LINUX_FUTEX_PRIVATE_FLAG); + + switch (args->op) { + case LINUX_FUTEX_WAIT: + + LINUX_CTR2(sys_futex, "WAIT val %d uaddr %p", + args->val, args->uaddr); +#ifdef DEBUG + if (ldebug(sys_futex)) + printf(ARGS(sys_futex, "futex_wait val %d uaddr %p"), + args->val, args->uaddr); +#endif + error = futex_get(args->uaddr, &wp, &f, FUTEX_CREATE_WP); + if (error) + return (error); + error = copyin(args->uaddr, &val, sizeof(val)); + if (error) { + LINUX_CTR1(sys_futex, "WAIT copyin failed %d", + error); + futex_put(f, wp); + return (error); + } + if (val != args->val) { + LINUX_CTR3(sys_futex, "WAIT uaddr %p val %d != uval %d", + args->uaddr, args->val, val); + futex_put(f, wp); + return (EWOULDBLOCK); + } + + error = futex_wait(f, wp, args->timeout); + break; + + case LINUX_FUTEX_WAKE: + + LINUX_CTR2(sys_futex, "WAKE val %d uaddr %p", + args->val, args->uaddr); + + /* + * XXX: Linux is able to cope with different addresses + * corresponding to the same mapped memory in the sleeping + * and waker process(es). + */ +#ifdef DEBUG + if (ldebug(sys_futex)) + printf(ARGS(sys_futex, "futex_wake val %d uaddr %p"), + args->val, args->uaddr); +#endif + error = futex_get(args->uaddr, NULL, &f, FUTEX_DONTCREATE); + if (error) + return (error); + if (f == NULL) { + td->td_retval[0] = 0; + return (error);; + } + td->td_retval[0] = futex_wake(f, args->val); + futex_put(f, NULL); + break; + + case LINUX_FUTEX_CMP_REQUEUE: + + LINUX_CTR5(sys_futex, "CMP_REQUEUE uaddr %p " + "val %d val3 %d uaddr2 %p val2 %d", + args->uaddr, args->val, args->val3, args->uaddr2, + (int)(unsigned long)args->timeout); + +#ifdef DEBUG + if (ldebug(sys_futex)) + printf(ARGS(sys_futex, "futex_cmp_requeue uaddr %p " + "val %d val3 %d uaddr2 %p val2 %d"), + args->uaddr, args->val, args->val3, args->uaddr2, + (int)(unsigned long)args->timeout); +#endif + + /* + * Linux allows this, we would not, it is an incorrect + * usage of declared ABI, so return EINVAL. + */ + if (args->uaddr == args->uaddr2) + return (EINVAL); + error = futex_get0(args->uaddr, &f, 0); + if (error) + return (error); + + /* + * To avoid deadlocks return EINVAL if second futex + * exists at this time. Otherwise create the new futex + * and ignore false positive LOR which thus happens. + * + * Glibc fall back to FUTEX_WAKE in case of any error + * returned by FUTEX_CMP_REQUEUE. + */ + error = futex_get0(args->uaddr2, &f2, FUTEX_DONTEXISTS); + if (error) { + futex_put(f, NULL); + return (error); + } + error = copyin(args->uaddr, &val, sizeof(val)); + if (error) { + LINUX_CTR1(sys_futex, "CMP_REQUEUE copyin failed %d", + error); + futex_put(f2, NULL); + futex_put(f, NULL); + return (error); + } + if (val != args->val3) { + LINUX_CTR2(sys_futex, "CMP_REQUEUE val %d != uval %d", + args->val, val); + futex_put(f2, NULL); + futex_put(f, NULL); + return (EAGAIN); + } + + nrwake = (int)(unsigned long)args->timeout; + td->td_retval[0] = futex_requeue(f, args->val, f2, nrwake); + futex_put(f2, NULL); + futex_put(f, NULL); + break; + + case LINUX_FUTEX_WAKE_OP: + + LINUX_CTR5(sys_futex, "WAKE_OP " + "uaddr %p op %d val %x uaddr2 %p val3 %x", + args->uaddr, args->op, args->val, + args->uaddr2, args->val3); + +#ifdef DEBUG + if (ldebug(sys_futex)) + printf(ARGS(sys_futex, "futex_wake_op " + "uaddr %p op %d val %x uaddr2 %p val3 %x"), + args->uaddr, args->op, args->val, + args->uaddr2, args->val3); +#endif + error = futex_get0(args->uaddr, &f, 0); + if (error) + return (error); + if (args->uaddr != args->uaddr2) + error = futex_get0(args->uaddr2, &f2, 0); + if (error) { + futex_put(f, NULL); + return (error); + } + + /* + * This function returns positive number as results and + * negative as errors + */ + op_ret = futex_atomic_op(td, args->val3, args->uaddr2); + + if (op_ret < 0) { + /* XXX: We don't handle the EFAULT yet. */ + if (op_ret != -EFAULT) { + if (f2 != NULL) + futex_put(f2, NULL); + futex_put(f, NULL); + return (-op_ret); + } + if (f2 != NULL) + futex_put(f2, NULL); + futex_put(f, NULL); + return (EFAULT); + } + + ret = futex_wake(f, args->val); + + if (op_ret > 0) { + op_ret = 0; + nrwake = (int)(unsigned long)args->timeout; + + if (f2 != NULL) + op_ret += futex_wake(f2, nrwake); + else + op_ret += futex_wake(f, nrwake); + ret += op_ret; + + } + if (f2 != NULL) + futex_put(f2, NULL); + futex_put(f, NULL); + td->td_retval[0] = ret; + break; + + case LINUX_FUTEX_LOCK_PI: + /* not yet implemented */ + return (ENOSYS); + + case LINUX_FUTEX_UNLOCK_PI: + /* not yet implemented */ + return (ENOSYS); + + case LINUX_FUTEX_TRYLOCK_PI: + /* not yet implemented */ + return (ENOSYS); + + case LINUX_FUTEX_REQUEUE: + + /* + * Glibc does not use this operation since version 2.3.3, + * as it is racy and replaced by FUTEX_CMP_REQUEUE operation. + * Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when + * FUTEX_REQUEUE returned EINVAL. + */ + em = em_find(td->td_proc, EMUL_DONTLOCK); + if (em->used_requeue == 0) { + printf("linux(%s (%d)) sys_futex: " + "unsupported futex_requeue op\n", + td->td_proc->p_comm, td->td_proc->p_pid); + em->used_requeue = 1; + } + return (EINVAL); + + default: + printf("linux_sys_futex: unknown op %d\n", args->op); + return (ENOSYS); + } + + return (error); +} + +int +linux_set_robust_list(struct thread *td, struct linux_set_robust_list_args *args) +{ + struct linux_emuldata *em; + +#ifdef DEBUG + if (ldebug(set_robust_list)) + printf(ARGS(set_robust_list, "head %p len %d"), + args->head, args->len); +#endif + + if (args->len != sizeof(struct linux_robust_list_head)) + return (EINVAL); + + em = em_find(td->td_proc, EMUL_DOLOCK); + em->robust_futexes = args->head; + EMUL_UNLOCK(&emul_lock); + + return (0); +} + +int +linux_get_robust_list(struct thread *td, struct linux_get_robust_list_args *args) +{ + struct linux_emuldata *em; + struct linux_robust_list_head *head; + l_size_t len = sizeof(struct linux_robust_list_head); + int error = 0; + +#ifdef DEBUG + if (ldebug(get_robust_list)) + printf(ARGS(get_robust_list, "")); +#endif + + if (!args->pid) { + em = em_find(td->td_proc, EMUL_DONTLOCK); + head = em->robust_futexes; + } else { + struct proc *p; + + p = pfind(args->pid); + if (p == NULL) + return (ESRCH); + + em = em_find(p, EMUL_DONTLOCK); + /* XXX: ptrace? */ + if (priv_check(td, PRIV_CRED_SETUID) || + priv_check(td, PRIV_CRED_SETEUID) || + p_candebug(td, p)) + return (EPERM); + head = em->robust_futexes; + + PROC_UNLOCK(p); + } + + error = copyout(&len, args->len, sizeof(l_size_t)); + if (error) + return (EFAULT); + + error = copyout(head, args->head, sizeof(struct linux_robust_list_head)); + + return (error); +} + +static int +handle_futex_death(struct proc *p, uint32_t *uaddr, int pi) +{ + uint32_t uval, nval, mval; + struct futex *f; + int error; + +retry: + if (copyin(uaddr, &uval, 4)) + return (EFAULT); + if ((uval & FUTEX_TID_MASK) == p->p_pid) { + mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED; + nval = casuword32(uaddr, uval, mval); + + if (nval == -1) + return (EFAULT); + + if (nval != uval) + goto retry; + + if (!pi && (uval & FUTEX_WAITERS)) { + error = futex_get(uaddr, NULL, &f, + FUTEX_DONTCREATE); + if (error) + return (error); + if (f != NULL) { + futex_wake(f, 1); + futex_put(f, NULL); + } + } + } + + return (0); +} + +static int +fetch_robust_entry(struct linux_robust_list **entry, + struct linux_robust_list **head, int *pi) +{ + l_ulong uentry; + + if (copyin((const void *)head, &uentry, sizeof(l_ulong))) + return (EFAULT); + + *entry = (void *)(uentry & ~1UL); + *pi = uentry & 1; + + return (0); +} + +/* This walks the list of robust futexes releasing them. */ +void +release_futexes(struct proc *p) +{ + struct linux_robust_list_head *head = NULL; + struct linux_robust_list *entry, *next_entry, *pending; + unsigned int limit = 2048, pi, next_pi, pip; + struct linux_emuldata *em; + l_long futex_offset; + int rc; + + em = em_find(p, EMUL_DONTLOCK); + head = em->robust_futexes; + + if (head == NULL) + return; + + if (fetch_robust_entry(&entry, PTRIN(&head->list.next), &pi)) + return; + + if (copyin(&head->futex_offset, &futex_offset, sizeof(futex_offset))) + return; + + if (fetch_robust_entry(&pending, PTRIN(&head->pending_list), &pip)) + return; + + while (entry != &head->list) { + rc = fetch_robust_entry(&next_entry, PTRIN(&entry->next), &next_pi); + + if (entry != pending) + if (handle_futex_death(p, (uint32_t *)entry + futex_offset, pi)) + return; + if (rc) + return; + + entry = next_entry; + pi = next_pi; + + if (!--limit) + break; + + sched_relinquish(curthread); + } + + if (pending) + handle_futex_death(p, (uint32_t *)pending + futex_offset, pip); +} |