From: Serge E. Hallyn <serue@xxxxxxxxxx>
Error messages are both sent to an optional user-provided logfile,
and, if CONFIG_CHECKPOINT_DEBUG=y, sent to syslog.
Changelog:
Oct 29: Split ckpt_log_error() into ckpt_log_error_v() and have
ckpt_write_err() call it to duplicate the checkpoint
error message into the optional user-provided log file and
(if CONFIG_CHECKPOINT_DEBUG=y) syslog as well.
Define a fn writing an error prefix (containing
current->pid etc) for ckpt_error().
Oct 28: Don't use a third va_args, and use smaller on-stack
buffer (mhelsley comments). It still might be cleaner
to always kmalloc, but always using two kmallocs per
ckpt_error is getting kinda gross... (open to comments
on that).
Oct 26: Per Oren suggestion, return -EBADF for bad
logfile in ckpt_ctx_alloc().
Signed-off-by: Serge E. Hallyn <serue@xxxxxxxxxx>
---
checkpoint/checkpoint.c | 8 +++-
checkpoint/objhash.c | 2 +
checkpoint/sys.c | 91 ++++++++++++++++++++++++++++++++++----
include/linux/checkpoint.h | 5 ++
include/linux/checkpoint_types.h | 5 ++
include/linux/syscalls.h | 5 +-
6 files changed, 103 insertions(+), 13 deletions(-)
diff --git a/checkpoint/checkpoint.c b/checkpoint/checkpoint.c
index 35fce15..30ec622 100644
--- a/checkpoint/checkpoint.c
+++ b/checkpoint/checkpoint.c
@@ -123,8 +123,6 @@ static void __ckpt_generate_err(struct ckpt_ctx *ctx, char *fmt, va_list ap)
va_end(aq);
kfree(format);
-
- ckpt_debug("c/r: checkpoint error: %s\n", str);
}
/**
@@ -140,9 +138,15 @@ void __ckpt_write_err(struct ckpt_ctx *ctx, char *fmt, ...)
{
va_list ap;
+ /* write to checkpoint file */
va_start(ap, fmt);
__ckpt_generate_err(ctx, fmt, ap);
va_end(ap);
+
+ /* write to user log and syslog */
+ va_start(ap, fmt);
+ ckpt_log_error_v(ctx, fmt, ap);
+ va_end(ap);
}
/**
diff --git a/checkpoint/objhash.c b/checkpoint/objhash.c
index a152e69..25b9c10 100644
--- a/checkpoint/objhash.c
+++ b/checkpoint/objhash.c
@@ -858,6 +858,8 @@ int ckpt_obj_contained(struct ckpt_ctx *ctx)
/* account for ctx->file reference (if in the table already) */
ckpt_obj_users_inc(ctx, ctx->file, 1);
+ if (ctx->logfile)
+ ckpt_obj_users_inc(ctx, ctx->logfile, 1);
/* account for ctx->root_nsproxy reference (if in the table already) */
ckpt_obj_users_inc(ctx, ctx->root_nsproxy, 1);
diff --git a/checkpoint/sys.c b/checkpoint/sys.c
index 9b2de18..736606d 100644
--- a/checkpoint/sys.c
+++ b/checkpoint/sys.c
@@ -204,6 +204,8 @@ static void ckpt_ctx_free(struct ckpt_ctx *ctx)
if (ctx->file)
fput(ctx->file);
+ if (ctx->logfile)
+ fput(ctx->logfile);
ckpt_obj_hash_free(ctx);
path_put(&ctx->fs_mnt);
@@ -220,12 +222,13 @@ static void ckpt_ctx_free(struct ckpt_ctx *ctx)
put_task_struct(ctx->root_freezer);
kfree(ctx->pids_arr);
+ kfree(ctx->error_buf);
kfree(ctx);
}
static struct ckpt_ctx *ckpt_ctx_alloc(int fd, unsigned long uflags,
- unsigned long kflags)
+ unsigned long kflags, int logfd)
{
struct ckpt_ctx *ctx;
int err;
@@ -249,11 +252,23 @@ static struct ckpt_ctx *ckpt_ctx_alloc(int fd, unsigned long uflags,
spin_lock_init(&ctx->lock);
#endif
+ err = -ENOMEM;
+ ctx->error_buf = kmalloc(CKPT_ERR_BUFSZ, GFP_KERNEL);
+ if (!ctx->error_buf)
+ goto err;
+ mutex_init(&ctx->error_buf_mutex);
+
err = -EBADF;
ctx->file = fget(fd);
if (!ctx->file)
goto err;
+ if (logfd != -1) {
+ ctx->logfile = fget(logfd);
+ if (!ctx->logfile)
+ goto err;
+ }
+
err = -ENOMEM;
if (ckpt_obj_hash_alloc(ctx) < 0)
goto err;
@@ -351,8 +366,7 @@ int walk_task_subtree(struct task_struct *root,
* PREFMT is constructed from @fmt by subtituting format snippets
* according to the contents of @fmt. The format characters in
* @fmt can be %(E) (error), %(O) (objref), %(P) (pointer), %(S) (string),
- * %(C) (bytes read/written out of checkpoint image so far), * and %(V)
- * (variable/symbol). For example, %(E) will generate a "err %d"
+ * and %(V) (variable/symbol). For example, %(E) will generate a "err %d"
* in PREFMT.
*
* If @fmt begins with %(T), PREFMT will begin with "pid %d tsk %s"
@@ -370,8 +384,6 @@ int walk_task_subtree(struct task_struct *root,
*
* Here, T is simply passed, E expects an integer (err), O expects an
* integer (objref), and the last argument matches the format string.
- *
- * XXX Do we want 'T' and 'C' to simply always be prepended?
*/
char *ckpt_generate_fmt(struct ckpt_ctx *ctx, char *fmt)
{
@@ -435,6 +447,66 @@ char *ckpt_generate_fmt(struct ckpt_ctx *ctx, char *fmt)
return format;
}
+/*
+ * called only by ckpt_log_error_v() to write out a prefix, which
+ * looks like:
+ * [current->pid]=[task_pid_vnr(current)]:[ctx->total]:[ctx->errno]
+ * the ctx->error_buf_mutex is held by caller, so we are free to
+ * write to ctx->error_buf_mutex. We also can assume that ctx is valid.
+ * Returns the number of characters written (not including trailing \0).
+ */
+static int ckpt_write_error_prefix(struct ckpt_ctx *ctx)
+{
+ return snprintf(ctx->error_buf, CKPT_ERR_BUFSZ, "[%d]=[%d]:[%lld]:[%d] ",
+ current->pid, task_pid_vnr(current), ctx->total,
+ ctx->errno);
+}
+
+void ckpt_log_error_v(struct ckpt_ctx *ctx, char *fmt, va_list ap)
+{
+ mm_segment_t fs;
+ char *format;
+ struct file *file = ctx->logfile;
+ char *bufp;
+ va_list aq;
+ int count, len;
+
+ format = ckpt_generate_fmt(ctx, fmt);
+ mutex_lock(&ctx->error_buf_mutex);
+ bufp = ctx->error_buf;
+ len = ckpt_write_error_prefix(ctx);
+ va_copy(aq, ap);
+ count = vsnprintf(bufp+len, CKPT_ERR_BUFSZ-len, format ? : fmt, aq);
+ va_end(aq);
+ count += len;
+ if (count > CKPT_ERR_BUFSZ) {
+ printk(KERN_WARNING "%s:%s:%d error string too long (%d)\n",
+ __FILE__, __func__, __LINE__, count);
+ bufp[CKPT_ERR_BUFSZ-1] = '\0';
+ }
+
+ fs = get_fs();
+ set_fs(KERNEL_DS);
+ _ckpt_kwrite(file, bufp, count);
+ set_fs(fs);
+
+ ckpt_debug("%s", bufp);
+ mutex_unlock(&ctx->error_buf_mutex);
+ kfree(format);
+}
+
+void ckpt_log_error(struct ckpt_ctx *ctx, char *fmt, ...)
+{
+ va_list ap;
+
+ if (!ctx || !ctx->logfile)
+ return;
+
+ va_start(ap, fmt);
+ ckpt_log_error_v(ctx, fmt, ap);
+ va_end(ap);
+}
+
/**
* sys_checkpoint - checkpoint a container
* @pid: pid of the container init(1) process
@@ -444,7 +516,8 @@ char *ckpt_generate_fmt(struct ckpt_ctx *ctx, char *fmt)
* Returns positive identifier on success, 0 when returning from restart
* or negative value on error
*/
-SYSCALL_DEFINE3(checkpoint, pid_t, pid, int, fd, unsigned long, flags)
+SYSCALL_DEFINE4(checkpoint, pid_t, pid, int, fd, unsigned long, flags,
+ int, logfd)
{
struct ckpt_ctx *ctx;
long ret;
@@ -457,7 +530,7 @@ SYSCALL_DEFINE3(checkpoint, pid_t, pid, int, fd, unsigned long, flags)
if (pid == 0)
pid = task_pid_vnr(current);
- ctx = ckpt_ctx_alloc(fd, flags, CKPT_CTX_CHECKPOINT);
+ ctx = ckpt_ctx_alloc(fd, flags, CKPT_CTX_CHECKPOINT, logfd);
if (IS_ERR(ctx))
return PTR_ERR(ctx);
@@ -479,7 +552,7 @@ SYSCALL_DEFINE3(checkpoint, pid_t, pid, int, fd, unsigned long, flags)
* Returns negative value on error, or otherwise returns in the realm
* of the original checkpoint
*/
-SYSCALL_DEFINE3(restart, pid_t, pid, int, fd, unsigned long, flags)
+SYSCALL_DEFINE4(restart, pid_t, pid, int, fd, unsigned long, flags, int, logfd)
{
struct ckpt_ctx *ctx = NULL;
long ret;
@@ -492,7 +565,7 @@ SYSCALL_DEFINE3(restart, pid_t, pid, int, fd, unsigned long, flags)
return -EPERM;
if (pid)
- ctx = ckpt_ctx_alloc(fd, flags, CKPT_CTX_RESTART);
+ ctx = ckpt_ctx_alloc(fd, flags, CKPT_CTX_RESTART, logfd);
if (IS_ERR(ctx))
return PTR_ERR(ctx);
diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
index 8a1eaa7..d3348c5 100644
--- a/include/linux/checkpoint.h
+++ b/include/linux/checkpoint.h
@@ -372,6 +372,11 @@ static inline void restore_debug_free(struct ckpt_ctx *ctx) {}
#endif /* CONFIG_CHECKPOINT_DEBUG */
extern char *ckpt_generate_fmt(struct ckpt_ctx *ctx, char *fmt);
+extern void ckpt_log_error_v(struct ckpt_ctx *ctx, char *fmt, va_list ap);
+extern void ckpt_log_error(struct ckpt_ctx *ctx, char *fmt, ...);
+
+#define ckpt_error(ctx, fmt, args...) \
+ ckpt_log_error(ctx, "%s:%d " fmt, __func__, __LINE__, ## args);
#endif /* CONFIG_CHECKPOINT */
#endif /* __KERNEL__ */
diff --git a/include/linux/checkpoint_types.h b/include/linux/checkpoint_types.h
index 5cc11d9..57fd524 100644
--- a/include/linux/checkpoint_types.h
+++ b/include/linux/checkpoint_types.h
@@ -48,6 +48,7 @@ struct ckpt_ctx {
unsigned long oflags; /* restart: uflags from checkpoint */
struct file *file; /* input/output file */
+ struct file *logfile; /* debug log file */
loff_t total; /* total read/written */
atomic_t refcount;
@@ -85,6 +86,10 @@ struct ckpt_ctx {
struct list_head task_status; /* list of status for each task */
spinlock_t lock;
#endif
+
+#define CKPT_ERR_BUFSZ 1024
+ char *error_buf; /* used by ckpt_error() */
+ struct mutex error_buf_mutex;
};
#endif /* __KERNEL__ */
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 33bce6e..4fce331 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -754,8 +754,9 @@ asmlinkage long sys_pselect6(int, fd_set __user *, fd_set __user *,
asmlinkage long sys_ppoll(struct pollfd __user *, unsigned int,
struct timespec __user *, const sigset_t __user *,
size_t);
-asmlinkage long sys_checkpoint(pid_t pid, int fd, unsigned long flags);
-asmlinkage long sys_restart(pid_t pid, int fd, unsigned long flags);
+asmlinkage long sys_checkpoint(pid_t pid, int fd, unsigned long flags,
+ int logfd);
+asmlinkage long sys_restart(pid_t pid, int fd, unsigned long flags, int logfd);
int kernel_execve(const char *filename, char *const argv[], char *const envp[]);
--
1.6.1
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