[CRIU] [PATCH 1/2] lock: Introduce futex_t and appropriate helpers
Cyrill Gorcunov
gorcunov at openvz.org
Mon Mar 26 11:38:32 EDT 2012
Instead of open-coded u32 variables poking lets use
futex_t type and appropriate helpers where needed.
This should increase readability.
Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
---
cr-restore.c | 57 +++++++++++++------------
files.c | 29 +++++++------
include/files.h | 7 ++-
include/lock.h | 115 +++++++++++++++++++++++-----------------------------
include/restorer.h | 6 +-
restorer.c | 18 ++++----
6 files changed, 112 insertions(+), 120 deletions(-)
diff --git a/cr-restore.c b/cr-restore.c
index a3a3222..1787573 100644
--- a/cr-restore.c
+++ b/cr-restore.c
@@ -58,11 +58,11 @@
struct pipe_info {
unsigned int pipeid;
int pid;
- u32 real_pid; /* futex */
int read_fd;
int write_fd;
int status;
- u32 users; /* futex */
+ futex_t real_pid;
+ futex_t users;
};
struct shmem_id {
@@ -126,7 +126,7 @@ static void show_saved_pipes(void)
for (i = 0; i < nr_pipes; i++)
pr_info("\t\tpipeid %x pid %d users %d status %d\n",
pipes[i].pipeid, pipes[i].pid,
- pipes[i].users, pipes[i].status);
+ futex_get(&pipes[i].users), pipes[i].status);
}
static struct pipe_info *find_pipe(unsigned int pipeid)
@@ -153,7 +153,7 @@ static int shmem_wait_and_open(int pid, struct shmem_info *si)
si->pid, si->start, si->end);
pr_info("%d: Waiting for [%s] to appear\n", pid, path);
- cr_wait_until(&si->lock, 1);
+ futex_wait_until(&si->lock, 1);
pr_info("%d: Opening shmem [%s] \n", pid, path);
ret = open(path, O_RDWR);
@@ -212,7 +212,7 @@ static int collect_shmem(int pid, struct vma_entry *vi)
si->size = size;
si->fd = -1;
- cr_wait_init(&si->lock);
+ futex_init(&si->lock);
return 0;
}
@@ -290,7 +290,7 @@ static int collect_pipe(int pid, struct pipe_entry *e, int p_fd)
break;
}
} else
- pipes[i].users++;
+ futex_inc(&pipes[i].users);
return 0;
}
@@ -304,10 +304,11 @@ static int collect_pipe(int pid, struct pipe_entry *e, int p_fd)
pipes[nr_pipes].pipeid = e->pipeid;
pipes[nr_pipes].pid = pid;
- pipes[nr_pipes].users = 0;
pipes[nr_pipes].read_fd = -1;
pipes[nr_pipes].write_fd = -1;
+ futex_init(&pipes[nr_pipes].users);
+
switch (e->flags & O_ACCMODE) {
case O_RDONLY:
pipes[nr_pipes].status = PIPE_RDONLY;
@@ -399,7 +400,7 @@ static int prepare_shared(int ps_fd)
return -1;
}
task_entries->nr = 0;
- task_entries->start = CR_STATE_RESTORE;
+ futex_set(&task_entries->start, CR_STATE_RESTORE);
pipes = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, 0, 0);
if (pipes == MAP_FAILED) {
@@ -437,7 +438,7 @@ static int prepare_shared(int ps_fd)
}
if (!ret) {
- task_entries->nr_in_progress = task_entries->nr;
+ futex_set(&task_entries->nr_in_progress, task_entries->nr);
lseek(ps_fd, sizeof(u32), SEEK_SET);
@@ -664,18 +665,18 @@ static int create_pipe(int pid, struct pipe_entry *e, struct pipe_info *pi, int
if (reopen_pipe(pfd[1], &pi->write_fd, &pi->read_fd, pipes_fd))
return -1;
- cr_wait_set(&pi->real_pid, pid);
+ futex_set_and_wake(&pi->real_pid, pid);
pi->status |= PIPE_CREATED;
pr_info("\t%d: Done, waiting for others (users %d) on %d pid with r:%d w:%d\n",
- pid, pi->users, pi->real_pid, pi->read_fd, pi->write_fd);
+ pid, futex_get(&pi->users), futex_get(&pi->real_pid), pi->read_fd, pi->write_fd);
if (!pipe_is_rw(pi)) {
pr_info("\t%d: Waiting for %x pipe to attach (%d users left)\n",
- pid, e->pipeid, pi->users);
+ pid, e->pipeid, futex_get(&pi->users));
- cr_wait_until(&pi->users, 0);
+ futex_wait_until(&pi->users, 0);
if ((e->flags & O_ACCMODE) == O_WRONLY)
close_safe(&pi->read_fd);
@@ -717,7 +718,7 @@ static int attach_pipe(int pid, struct pipe_entry *e, struct pipe_info *pi, int
pr_info("\t%d: Waiting for pipe %x to appear\n",
pid, e->pipeid);
- cr_wait_while(&pi->real_pid, 0);
+ futex_wait_while(&pi->real_pid, 0);
if (move_img_fd(pipes_fd, e->fd))
return -1;
@@ -740,9 +741,9 @@ static int attach_pipe(int pid, struct pipe_entry *e, struct pipe_info *pi, int
goto out;
}
- sprintf(path, "/proc/%d/fd/%d", pi->real_pid, tmp);
+ sprintf(path, "/proc/%d/fd/%d", futex_get(&pi->real_pid), tmp);
pr_info("\t%d: Attaching pipe %s (%d users left)\n",
- pid, path, pi->users - 1);
+ pid, path, futex_get(&pi->users) - 1);
fd = open(path, e->flags);
if (fd < 0) {
@@ -754,7 +755,7 @@ static int attach_pipe(int pid, struct pipe_entry *e, struct pipe_info *pi, int
if (reopen_fd_as(e->fd, fd))
return -1;
- cr_wait_dec(&pi->users);
+ futex_dec_and_wake(&pi->users);
out:
tmp = set_fd_flags(e->fd, e->flags);
if (tmp < 0)
@@ -973,13 +974,13 @@ static int restore_one_zombie(int pid, int exit_code)
pr_info("Restoring zombie with %d code\n", exit_code);
if (task_entries != NULL) {
- cr_wait_dec(&task_entries->nr_in_progress);
- cr_wait_while(&task_entries->start, CR_STATE_RESTORE);
+ futex_dec_and_wake(&task_entries->nr_in_progress);
+ futex_wait_while(&task_entries->start, CR_STATE_RESTORE);
zombie_prepare_signals();
- cr_wait_dec(&task_entries->nr_in_progress);
- cr_wait_while(&task_entries->start, CR_STATE_RESTORE_SIGCHLD);
+ futex_dec_and_wake(&task_entries->nr_in_progress);
+ futex_wait_while(&task_entries->start, CR_STATE_RESTORE_SIGCHLD);
}
if (exit_code & 0x7f) {
@@ -1124,7 +1125,7 @@ static void sigchld_handler(int signal, siginfo_t *siginfo, void *data)
pr_err("%d killed by signal %d\n",
siginfo->si_pid, siginfo->si_status);
- cr_wait_set(&task_entries->nr_in_progress, -1);
+ futex_set_and_wake(&task_entries->nr_in_progress, -1);
}
static int restore_task_with_children(void *_arg)
@@ -1259,7 +1260,9 @@ static int restore_root_task(int fd, struct cr_options *opts)
return -1;
pr_info("Wait until all tasks are restored\n");
- ret = cr_wait_until_greater(&task_entries->nr_in_progress, 0);
+ futex_wait_while_gt(&task_entries->nr_in_progress, 0);
+ ret = (int)futex_get(&task_entries->nr_in_progress);
+
out:
if (ret < 0) {
pr_err("Someone can't be restored\n");
@@ -1268,9 +1271,9 @@ out:
return 1;
}
- cr_wait_set(&task_entries->nr_in_progress, task_entries->nr);
- cr_wait_set(&task_entries->start, CR_STATE_RESTORE_SIGCHLD);
- cr_wait_until(&task_entries->nr_in_progress, 0);
+ futex_set_and_wake(&task_entries->nr_in_progress, task_entries->nr);
+ futex_set_and_wake(&task_entries->start, CR_STATE_RESTORE_SIGCHLD);
+ futex_wait_until(&task_entries->nr_in_progress, 0);
ret = sigaction(SIGCHLD, &old_act, NULL);
if (ret < 0) {
@@ -1279,7 +1282,7 @@ out:
}
pr_info("Go on!!!\n");
- cr_wait_set(&task_entries->start, CR_STATE_COMPLETE);
+ futex_set_and_wake(&task_entries->start, CR_STATE_COMPLETE);
if (!opts->restore_detach)
wait(NULL);
diff --git a/files.c b/files.c
index 7055771..1c6fc11 100644
--- a/files.c
+++ b/files.c
@@ -75,7 +75,8 @@ static int collect_fd(int pid, struct fdinfo_entry *e)
le->pid = pid;
le->fd = e->addr;
- le->real_pid = 0;
+
+ futex_init(&le->real_pid);
for (i = 0; i < nr_fdinfo_descs; i++) {
desc = &fdinfo_descs[i];
@@ -83,7 +84,7 @@ static int collect_fd(int pid, struct fdinfo_entry *e)
if (desc->id != e->id)
continue;
- fdinfo_descs[i].users++;
+ futex_inc(&fdinfo_descs[i].users);
list_add(&le->list, &desc->list);
if (fdinfo_descs[i].pid < pid)
@@ -106,8 +107,8 @@ static int collect_fd(int pid, struct fdinfo_entry *e)
desc->id = e->id;
desc->addr = e->addr;
desc->pid = pid;
- desc->users = 1;
INIT_LIST_HEAD(&desc->list);
+ futex_set(&desc->users, 1);
list_add(&le->list, &desc->list);
nr_fdinfo_descs++;
@@ -275,7 +276,7 @@ static int open_transport_fd(int pid, struct fdinfo_entry *fe,
transport_name_gen(&saddr, &sun_len, getpid(), fe->addr);
pr_info("\t%d: Create transport fd for %lx users %d\n", pid,
- fe->addr, fi->users);
+ fe->addr, futex_get(&fi->users));
fle = find_fdinfo_list_entry(pid, fe->addr, fi);
@@ -295,7 +296,7 @@ static int open_transport_fd(int pid, struct fdinfo_entry *fe,
return -1;
pr_info("Wake up fdinfo pid=%d fd=%d\n", fle->pid, fle->fd);
- cr_wait_set(&fle->real_pid, getpid());
+ futex_set_and_wake(&fle->real_pid, getpid());
return 0;
}
@@ -318,7 +319,7 @@ static int open_fd(int pid, struct fdinfo_entry *fe,
if (reopen_fd_as((int)fe->addr, tmp))
return -1;
- if (fi->users == 1)
+ if (futex_get(&fi->users) == 1)
goto out;
sock = socket(PF_UNIX, SOCK_DGRAM, 0);
@@ -327,24 +328,24 @@ static int open_fd(int pid, struct fdinfo_entry *fe,
return -1;
}
- cr_wait_set(&fi->real_pid, getpid());
+ futex_set_and_wake(&fi->real_pid, getpid());
pr_info("\t%d: Create fd for %lx users %d\n", pid,
- fe->addr, fi->users);
+ fe->addr, futex_get(&fi->users));
list_for_each_entry(fle, &fi->list, list) {
int len;
- fi->users--;
+ futex_dec(&fi->users);
if (pid == fle->pid)
continue;
pr_info("Wait fdinfo pid=%d fd=%d\n", fle->pid, fle->fd);
- cr_wait_while(&fle->real_pid, 0);
+ futex_wait_while(&fle->real_pid, 0);
pr_info("Send fd %d to %s\n", (int)fe->addr, saddr.sun_path + 1);
- transport_name_gen(&saddr, &len, fle->real_pid, fle->fd);
+ transport_name_gen(&saddr, &len, futex_get(&fle->real_pid), fle->fd);
if (send_fd(sock, &saddr, len, fe->addr) < 0) {
pr_perror("Can't send file descriptor");
@@ -352,7 +353,7 @@ static int open_fd(int pid, struct fdinfo_entry *fe,
}
}
- BUG_ON(fi->users);
+ BUG_ON(futex_get(&fi->users));
close(sock);
out:
return 0;
@@ -376,7 +377,7 @@ static int receive_fd(int pid, struct fdinfo_entry *fe, struct fdinfo_desc *fi)
}
pr_info("\t%d: Receive fd for %lx users %d\n", pid,
- fe->addr, fi->users);
+ fe->addr, futex_get(&fi->users));
tmp = recv_fd(fe->addr);
if (tmp < 0) {
@@ -426,7 +427,7 @@ static int open_fdinfo(int pid, struct fdinfo_entry *fe, int *fdinfo_fd, int sta
return -1;
pr_info("\t%d: Got fd for %lx users %d\n", pid,
- fe->addr, fi->users);
+ fe->addr, futex_get(&fi->users));
BUG_ON(fe->type != FDINFO_REG);
diff --git a/include/files.h b/include/files.h
index e040380..fb8d952 100644
--- a/include/files.h
+++ b/include/files.h
@@ -3,6 +3,7 @@
#include "compiler.h"
#include "types.h"
+#include "lock.h"
#include "list.h"
#include "image.h"
@@ -25,8 +26,8 @@ struct fdinfo_desc {
u64 id;
u64 addr;
int pid;
- u32 real_pid; /* futex */
- u32 users; /* futex */
+ futex_t real_pid;
+ futex_t users;
struct list_head list;
};
@@ -34,7 +35,7 @@ struct fdinfo_list_entry {
struct list_head list;
int fd;
int pid;
- u32 real_pid;
+ futex_t real_pid;
};
extern int prepare_fds(int pid);
diff --git a/include/lock.h b/include/lock.h
index 157e2f3..1a5eb6b 100644
--- a/include/lock.h
+++ b/include/lock.h
@@ -11,86 +11,73 @@
#include "syscall.h"
#include "util.h"
-/*
- * Init futex @v value
- */
-static always_inline void cr_wait_init(u32 *v)
+typedef struct {
+ u32 raw;
+} futex_t;
+
+/* Get current futex @f value */
+static inline u32 futex_get(futex_t *f)
{
- u32 val = 0;
- atomic_set(v, val);
+ return atomic_get(&f->raw);
}
-/*
- * Set futex @v value to @val and wake up all waiters
- */
-static always_inline void cr_wait_set(u32 *v, u32 val)
+/* Set futex @f value to @v */
+static inline void futex_set(futex_t *f, u32 v)
{
- int ret;
-
- atomic_set(v, val);
-
- ret = sys_futex(v, FUTEX_WAKE, INT_MAX, NULL, NULL, 0);
- BUG_ON(ret < 0);
+ atomic_set(&f->raw, v);
}
-/*
- * Decrement futex @v value to @val and wake up all waiters
- */
-static always_inline void cr_wait_dec(u32 *v)
+#define futex_init(f) futex_set(f, 0)
+
+/* Wait on futex @__f value @__v become in condition @__c */
+#define futex_wait_if_cond(__f, __v, __cond) \
+ do { \
+ int ret; \
+ u32 tmp; \
+ \
+ while (1) { \
+ tmp = (__f)->raw; \
+ if (tmp __cond (__v)) \
+ break; \
+ ret = sys_futex(&(__f)->raw, FUTEX_WAIT,\
+ tmp, NULL, NULL, 0); \
+ BUG_ON(ret < 0 && ret != -EWOULDBLOCK); \
+ } \
+ } while (0)
+
+/* Set futex @f to @v and wake up all waiters */
+static inline void futex_set_and_wake(futex_t *f, u32 v)
{
- int ret;
-
- atomic_dec(v);
-
- ret = sys_futex(v, FUTEX_WAKE, INT_MAX, NULL, NULL, 0);
- BUG_ON(ret < 0);
+ atomic_set(&f->raw, v);
+ BUG_ON(sys_futex(&f->raw, FUTEX_WAKE, INT_MAX, NULL, NULL, 0) < 0);
}
-/*
- * Wait until futex @v value become @val
- */
-static always_inline void cr_wait_until(u32 *v, u32 val)
+/* Decrement futex @f value and wake up all waiters */
+static inline void futex_dec_and_wake(futex_t *f)
{
- int ret;
- u32 tmp;
-
- while (1) {
- tmp = *v;
- if (tmp == val)
- break;
- ret = sys_futex(v, FUTEX_WAIT, tmp, NULL, NULL, 0);
- BUG_ON(ret < 0 && ret != -EWOULDBLOCK);
- }
+ atomic_dec(&f->raw);
+ BUG_ON(sys_futex(&f->raw, FUTEX_WAKE, INT_MAX, NULL, NULL, 0) < 0);
}
-/*
- * Wait until futex @v value greater than @val
- */
-static always_inline s32 cr_wait_until_greater(u32 *v, s32 val)
-{
- int ret;
- s32 tmp;
+/* Plain increment futex @f value */
+static inline void futex_inc(futex_t *f) { f->raw++; }
- while (1) {
- tmp = *v;
- if (tmp <= val)
- break;
- ret = sys_futex(v, FUTEX_WAIT, tmp, NULL, NULL, 0);
- BUG_ON(ret < 0 && ret != -EWOULDBLOCK);
- }
+/* Plain decrement futex @f value */
+static inline void futex_dec(futex_t *f) { f->raw--; }
- return tmp;
-}
+/* Wait until futex @f value become @v */
+static inline void futex_wait_until(futex_t *f, u32 v)
+{ futex_wait_if_cond(f, v, ==); }
-/*
- * Wait while futex @v value is @val
- */
-static always_inline void cr_wait_while(u32 *v, u32 val)
-{
- int ret;
+/* Wait while futex @f value is greater than @v */
+static inline void futex_wait_while_gt(futex_t *f, u32 v)
+{ futex_wait_if_cond(f, v, <=); }
- while (*v == val) {
- ret = sys_futex(v, FUTEX_WAIT, val, NULL, NULL, 0);
+/* Wait while futex @f value is @v */
+static inline void futex_wait_while(futex_t *f, u32 v)
+{
+ while (f->raw == v) {
+ int ret = sys_futex(&f->raw, FUTEX_WAIT, v, NULL, NULL, 0);
BUG_ON(ret < 0 && ret != -EWOULDBLOCK);
}
}
diff --git a/include/restorer.h b/include/restorer.h
index 5801792..639e9f9 100644
--- a/include/restorer.h
+++ b/include/restorer.h
@@ -198,7 +198,7 @@ struct shmem_info {
unsigned long size;
int pid;
int fd;
- u32 lock; /* futex */
+ futex_t lock;
};
struct shmems {
@@ -216,8 +216,8 @@ enum {
struct task_entries {
int nr;
- u32 nr_in_progress;
- u32 start; //futex
+ futex_t nr_in_progress;
+ futex_t start;
};
static always_inline struct shmem_info *
diff --git a/restorer.c b/restorer.c
index 44233e6..889cd2f 100644
--- a/restorer.c
+++ b/restorer.c
@@ -46,7 +46,7 @@ static void sigchld_handler(int signal, siginfo_t *siginfo, void *data)
write_string(" killed by signal ");
write_num_n(siginfo->si_status);
- cr_wait_set(&task_entries->nr_in_progress, -1);
+ futex_set_and_wake(&task_entries->nr_in_progress, -1);
/* sa_restorer may be unmaped, so we can't go back to userspace*/
sys_kill(sys_getpid(), SIGSTOP);
sys_exit(1);
@@ -209,13 +209,13 @@ long restore_thread(struct thread_restore_args *args)
*/
restore_creds(NULL);
- cr_wait_dec(&task_entries->nr_in_progress);
+ futex_dec_and_wake(&task_entries->nr_in_progress);
write_num(sys_gettid());
write_string_n(": Restored");
- cr_wait_while(&task_entries->start, CR_STATE_RESTORE);
- cr_wait_dec(&task_entries->nr_in_progress);
+ futex_wait_while(&task_entries->start, CR_STATE_RESTORE);
+ futex_dec_and_wake(&task_entries->nr_in_progress);
new_sp = (long)rt_sigframe + 8;
asm volatile(
@@ -423,7 +423,7 @@ long restore_task(struct task_restore_core_args *args)
vma_entry->shmid);
if (entry && entry->pid == my_pid &&
entry->start == vma_entry->start)
- cr_wait_set(&entry->lock, 1);
+ futex_set_and_wake(&entry->lock, 1);
}
if (vma_entry->prot & PROT_WRITE)
@@ -652,20 +652,20 @@ long restore_task(struct task_restore_core_args *args)
restore_creds(&args->creds);
- cr_wait_dec(&args->task_entries->nr_in_progress);
+ futex_dec_and_wake(&args->task_entries->nr_in_progress);
write_num(sys_getpid());
write_string_n(": Restored");
- cr_wait_while(&args->task_entries->start, CR_STATE_RESTORE);
+ futex_wait_while(&args->task_entries->start, CR_STATE_RESTORE);
sys_sigaction(SIGCHLD, &args->sigchld_act, NULL);
- cr_wait_dec(&args->task_entries->nr_in_progress);
+ futex_dec_and_wake(&args->task_entries->nr_in_progress);
sys_close(args->logfd);
- cr_wait_while(&args->task_entries->start, CR_STATE_RESTORE_SIGCHLD);
+ futex_wait_while(&args->task_entries->start, CR_STATE_RESTORE_SIGCHLD);
/*
* The code that prepared the itimers makes shure the
--
1.7.7.6
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