X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=lttng-statedump-impl.c;h=864637dd457fc1321c9ca09fe23764704e55eb22;hb=fcf7fa335dc9b5119fccc23bb81fff546ce854ec;hp=d0e641a97ca70452508ccf618ebf9c594b67cb5b;hpb=cfcee1c794ba05c6f7e4b0f7e630f9ca5cba935f;p=lttng-modules.git

diff --git a/lttng-statedump-impl.c b/lttng-statedump-impl.c
index d0e641a9..864637dd 100644
--- a/lttng-statedump-impl.c
+++ b/lttng-statedump-impl.c
@@ -65,6 +65,7 @@
 #define CREATE_TRACE_POINTS
 #define TRACE_INCLUDE_PATH ../instrumentation/events/lttng-module
 #define TRACE_INCLUDE_FILE lttng-statedump
+#define LTTNG_INSTRUMENTATION
 #include "instrumentation/events/lttng-module/lttng-statedump.h"
 
 DEFINE_TRACE(lttng_statedump_block_device);
@@ -79,7 +80,7 @@ struct lttng_fd_ctx {
 	char *page;
 	struct lttng_session *session;
 	struct task_struct *p;
-	struct fdtable *fdt;
+	struct files_struct *files;
 };
 
 /*
@@ -219,13 +220,24 @@ int lttng_dump_one_fd(const void *p, struct file *file, unsigned int fd)
 	const struct lttng_fd_ctx *ctx = p;
 	const char *s = d_path(&file->f_path, ctx->page, PAGE_SIZE);
 	unsigned int flags = file->f_flags;
+	struct fdtable *fdt;
 
 	/*
 	 * We don't expose kernel internal flags, only userspace-visible
 	 * flags.
 	 */
 	flags &= ~FMODE_NONOTIFY;
-	if (test_bit(fd, ctx->fdt->close_on_exec))
+	fdt = files_fdtable(ctx->files);
+	/*
+	 * We need to check here again whether fd is within the fdt
+	 * max_fds range, because we might be seeing a different
+	 * files_fdtable() than iterate_fd(), assuming only RCU is
+	 * protecting the read. In reality, iterate_fd() holds
+	 * file_lock, which should ensure the fdt does not change while
+	 * the lock is taken, but we are not aware whether this is
+	 * guaranteed or not, so play safe.
+	 */
+	if (fd < fdt->max_fds && test_bit(fd, fdt->close_on_exec))
 		flags |= O_CLOEXEC;
 	if (IS_ERR(s)) {
 		struct dentry *dentry = file->f_path.dentry;
@@ -248,10 +260,15 @@ void lttng_enumerate_task_fd(struct lttng_session *session,
 		struct task_struct *p, char *tmp)
 {
 	struct lttng_fd_ctx ctx = { .page = tmp, .session = session, .p = p };
+	struct files_struct *files;
 
 	task_lock(p);
-	ctx.fdt = files_fdtable(p->files);
-	lttng_iterate_fd(p->files, 0, lttng_dump_one_fd, &ctx);
+	files = p->files;
+	if (!files)
+		goto end;
+	ctx.files = files;
+	lttng_iterate_fd(files, 0, lttng_dump_one_fd, &ctx);
+end:
 	task_unlock(p);
 }
 
@@ -362,6 +379,9 @@ int lttng_list_interrupts(struct lttng_session *session)
 }
 #endif
 
+/*
+ * Called with task lock held.
+ */
 static
 void lttng_statedump_process_ns(struct lttng_session *session,
 		struct task_struct *p,
@@ -373,8 +393,18 @@ void lttng_statedump_process_ns(struct lttng_session *session,
 	struct nsproxy *proxy;
 	struct pid_namespace *pid_ns;
 
+	/*
+	 * Back and forth on locking strategy within Linux upstream for nsproxy.
+	 * See Linux upstream commit 728dba3a39c66b3d8ac889ddbe38b5b1c264aec3
+	 * "namespaces: Use task_lock and not rcu to protect nsproxy"
+	 * for details.
+	 */
+#if (LINUX_VERSION_CODE < KERNEL_VERSION(3,17,0))
 	rcu_read_lock();
 	proxy = task_nsproxy(p);
+#else /* #if (LINUX_VERSION_CODE < KERNEL_VERSION(3,17,0)) */
+	proxy = p->nsproxy;
+#endif /* #else #if (LINUX_VERSION_CODE < KERNEL_VERSION(3,17,0)) */
 	if (proxy) {
 		pid_ns = lttng_get_proxy_pid_ns(proxy);
 		do {
@@ -386,7 +416,9 @@ void lttng_statedump_process_ns(struct lttng_session *session,
 		trace_lttng_statedump_process_state(session,
 			p, type, mode, submode, status, NULL);
 	}
+#if (LINUX_VERSION_CODE < KERNEL_VERSION(3,17,0))
 	rcu_read_unlock();
+#endif /* #if (LINUX_VERSION_CODE < KERNEL_VERSION(3,17,0)) */
 }
 
 static