From 361c023a0d376536a894ca34344cb626905ad0ab Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Fri, 25 Jan 2013 12:25:38 -0500 Subject: [PATCH] Fix: statedump: missing locking, use lttng_iterate_fd - Take a spinlock around use of dentry->d_name.name. - Use lttng_iterate_fd wrapper (and thus iterate_fd() from Linux kernels from v3.7 and onward). Suggested-by: Al Viro Signed-off-by: Mathieu Desnoyers --- Makefile | 3 ++- lttng-statedump-impl.c | 50 ++++++++++++++++++++++++------------------ 2 files changed, 31 insertions(+), 22 deletions(-) diff --git a/Makefile b/Makefile index 4cc8b6bf..2da72989 100644 --- a/Makefile +++ b/Makefile @@ -23,7 +23,8 @@ lttng-tracer-objs := lttng-events.o lttng-abi.o \ lttng-context-hostname.o wrapper/random.o obj-m += lttng-statedump.o -lttng-statedump-objs := lttng-statedump-impl.o wrapper/irqdesc.o +lttng-statedump-objs := lttng-statedump-impl.o wrapper/irqdesc.o \ + wrapper/fdtable.o ifneq ($(CONFIG_HAVE_SYSCALL_TRACEPOINTS),) lttng-tracer-objs += lttng-syscalls.o probes/lttng-probe-user.o diff --git a/lttng-statedump-impl.c b/lttng-statedump-impl.c index bbe0a156..04acf6ef 100644 --- a/lttng-statedump-impl.c +++ b/lttng-statedump-impl.c @@ -49,6 +49,7 @@ #include "lttng-events.h" #include "wrapper/irqdesc.h" #include "wrapper/spinlock.h" +#include "wrapper/fdtable.h" #ifdef CONFIG_GENERIC_HARDIRQS #include @@ -60,6 +61,12 @@ #define TRACE_INCLUDE_FILE lttng-statedump #include "instrumentation/events/lttng-module/lttng-statedump.h" +struct lttng_fd_ctx { + char *page; + struct lttng_session *session; + struct task_struct *p; +}; + /* * Protected by the trace lock. */ @@ -141,34 +148,35 @@ int lttng_enumerate_network_ip_interface(struct lttng_session *session) } #endif /* CONFIG_INET */ +static +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); + + if (IS_ERR(s)) { + struct dentry *dentry = file->f_path.dentry; + + /* Make sure we give at least some info */ + spin_lock(&dentry->d_lock); + trace_lttng_statedump_file_descriptor(ctx->session, ctx->p, fd, + dentry->d_name.name); + spin_unlock(&dentry->d_lock); + goto end; + } + trace_lttng_statedump_file_descriptor(ctx->session, ctx->p, fd, s); +end: + return 0; +} static void lttng_enumerate_task_fd(struct lttng_session *session, struct task_struct *p, char *tmp) { - struct fdtable *fdt; - struct file *filp; - unsigned int i; - const unsigned char *path; + struct lttng_fd_ctx ctx = { .page = tmp, .session = session, .p = p }; task_lock(p); - if (!p->files) - goto unlock_task; - spin_lock(&p->files->file_lock); - fdt = files_fdtable(p->files); - for (i = 0; i < fdt->max_fds; i++) { - filp = fcheck_files(p->files, i); - if (!filp) - continue; - path = d_path(&filp->f_path, tmp, PAGE_SIZE); - /* Make sure we give at least some info */ - trace_lttng_statedump_file_descriptor(session, p, i, - IS_ERR(path) ? - filp->f_dentry->d_name.name : - path); - } - spin_unlock(&p->files->file_lock); -unlock_task: + lttng_iterate_fd(p->files, 0, lttng_dump_one_fd, &ctx); task_unlock(p); } -- 2.34.1