From: Xiang Rui <rui.xiang@xxxxxxxxxx>
This patch add a struct syslog_namespace which contains the necessary member
when handling syslog.
We realize gut_syslog_ns and put_syslog_ns API, and syslog_ns is initialized
by init_syslog_ns. CONFIG_SYSLOG_NS is defined to allow to create syslog_ns.
Signed-off-by: Xiang Rui <rui.xiang@xxxxxxxxxx>
Signed-off-by: Libo Chen <clbchenlibo.chen@xxxxxxxxxx>
---
include/linux/syslog_namespace.h | 78 ++++++++++++++++++++++++++++++++++++++
init/Kconfig | 7 +++
kernel/Makefile | 1 +
kernel/syslog_namespace.c | 31 +++++++++++++++
4 files changed, 117 insertions(+), 0 deletions(-)
create mode 100644 include/linux/syslog_namespace.h
create mode 100644 kernel/syslog_namespace.c
diff --git a/include/linux/syslog_namespace.h b/include/linux/syslog_namespace.h
new file mode 100644
index 0000000..8c8ac5a
--- /dev/null
+++ b/include/linux/syslog_namespace.h
@@ -0,0 +1,78 @@
+#ifndef _LINUX_SYSLOG_NAMESPACE_H
+#define _LINUX_SYSLOG_NAMESPACE_H
+
+#include <linux/kref.h>
+
+/* record buffer */
+#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
+#define LOG_ALIGN 4
+#else
+#define LOG_ALIGN __alignof__(struct log)
+#endif
+
+#define CONTAINER_BUF_LEN 4096
+
+#define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
+
+struct syslog_namespace {
+ struct kref kref; /* syslog_ns reference count & control */
+
+ raw_spinlock_t logbuf_lock; /* access conflict locker */
+
+ /* index and sequence number of the first record stored in the buffer */
+ u64 log_first_seq;
+ u32 log_first_idx;
+
+ /* index and sequence number of the next record stored in the buffer */
+ u64 log_next_seq;
+ u32 log_next_idx;
+
+ /* the next printk record to read after the last 'clear' command */
+ u64 clear_seq;
+ u32 clear_idx;
+
+ char *log_buf;
+ u32 log_buf_len;
+
+ /* the next printk record to write to the console */
+ u64 console_seq;
+ u32 console_idx;
+
+ /* the next printk record to read by syslog(READ) or /proc/kmsg */
+ u64 syslog_seq;
+ u32 syslog_idx;
+ int syslog_prev;
+ size_t syslog_partial;
+};
+
+extern struct syslog_namespace init_syslog_ns;
+
+#ifdef CONFIG_SYSLOG_NS
+extern void free_syslog_ns(struct kref *kref);
+static inline struct syslog_namespace *get_syslog_ns(
+ struct syslog_namespace *ns)
+{
+ if (ns != &init_syslog_ns)
+ kref_get(&ns->kref);
+ return ns;
+}
+
+static inline void put_syslog_ns(struct syslog_namespace *ns)
+{
+ if (ns != &init_syslog_ns)
+ kref_put(&ns->kref, free_syslog_ns);
+}
+
+#else
+static inline struct syslog_namespace *get_syslog_ns(
+ struct syslog_namespace *ns)
+{
+ return ns;
+}
+
+static inline void put_syslog_ns(struct syslog_namespace *ns)
+{
+}
+#endif
+
+#endif
diff --git a/init/Kconfig b/init/Kconfig
index 6fdd6e3..82771e0 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -988,6 +988,13 @@ config NET_NS
Allow user space to create what appear to be multiple instances
of the network stack.
+config SYSLOG_NS
+ bool "Syslog namespace"
+ default y
+ help
+ Allow containers to use syslog namespaces to provide different
+ syslog for containers.
+
endif # NAMESPACES
config UIDGID_CONVERTED
diff --git a/kernel/Makefile b/kernel/Makefile
index 0dfeca4..cb3cba0 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -28,6 +28,7 @@ obj-y += power/
ifeq ($(CONFIG_CHECKPOINT_RESTORE),y)
obj-$(CONFIG_X86) += kcmp.o
endif
+obj-$(CONFIG_SYSLOG_NS) += syslog_namespace.o
obj-$(CONFIG_FREEZER) += freezer.o
obj-$(CONFIG_PROFILING) += profile.o
obj-$(CONFIG_STACKTRACE) += stacktrace.o
diff --git a/kernel/syslog_namespace.c b/kernel/syslog_namespace.c
new file mode 100644
index 0000000..9482927
--- /dev/null
+++ b/kernel/syslog_namespace.c
@@ -0,0 +1,31 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2 of the
+ * License.
+ */
+
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/syslog_namespace.h>
+
+static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
+
+struct syslog_namespace init_syslog_ns = {
+ .kref = {
+ .refcount = ATOMIC_INIT(2),
+ },
+ .logbuf_lock = __RAW_SPIN_LOCK_UNLOCKED(init_syslog_ns.logbuf_lock),
+ .log_buf_len = __LOG_BUF_LEN,
+ .log_buf = __log_buf,
+};
+EXPORT_SYMBOL_GPL(init_syslog_ns);
+
+void free_syslog_ns(struct kref *kref)
+{
+ struct syslog_namespace *ns;
+ ns = container_of(kref, struct syslog_namespace, kref);
+
+ kfree(ns->log_buf);
+ kfree(ns);
+}
--
1.7.1
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