You forgot to add Miklos again. Miklos, have any comments on this patch? Or can you give a "Reviewed-by"?
-- Steve On Wed, 18 Apr 2018 10:40:14 -0700 Song Liu <[email protected]> wrote: > As Miklos reported and suggested: > > This pattern repeats two times in trace_uprobe.c and in > kernel/events/core.c as well: > > ret = kern_path(filename, LOOKUP_FOLLOW, &path); > if (ret) > goto fail_address_parse; > > inode = igrab(d_inode(path.dentry)); > path_put(&path); > > And it's wrong. You can only hold a reference to the inode if you > have an active ref to the superblock as well (which is normally > through path.mnt) or holding s_umount. > > This way unmounting the containing filesystem while the tracepoint is > active will give you the "VFS: Busy inodes after unmount..." message > and a crash when the inode is finally put. > > Solution: store path instead of inode. > > This patch fixes two instances in trace_uprobe.c. > > Fixes: f3f096cfedf8 ("tracing: Provide trace events interface for uprobes") > Fixes: 33ea4b24277b ("perf/core: Implement the 'perf_uprobe' PMU") > Cc: Steven Rostedt <[email protected]> > Cc: Ingo Molnar <[email protected]> > Cc: Howard McLauchlan <[email protected]> > Cc: Josef Bacik <[email protected]> > Cc: Srikar Dronamraju <[email protected]> > Reported-by: Miklos Szeredi <[email protected]> > Signed-off-by: Song Liu <[email protected]> > --- > kernel/trace/trace_uprobe.c | 49 > +++++++++++++++------------------------------ > 1 file changed, 16 insertions(+), 33 deletions(-) > > diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c > index 34fd0e0..d9ee522c 100644 > --- a/kernel/trace/trace_uprobe.c > +++ b/kernel/trace/trace_uprobe.c > @@ -55,7 +55,7 @@ struct trace_uprobe { > struct list_head list; > struct trace_uprobe_filter filter; > struct uprobe_consumer consumer; > - struct inode *inode; > + struct path path; > char *filename; > unsigned long offset; > unsigned long nhit; > @@ -289,7 +289,7 @@ static void free_trace_uprobe(struct trace_uprobe *tu) > for (i = 0; i < tu->tp.nr_args; i++) > traceprobe_free_probe_arg(&tu->tp.args[i]); > > - iput(tu->inode); > + path_put(&tu->path); > kfree(tu->tp.call.class->system); > kfree(tu->tp.call.name); > kfree(tu->filename); > @@ -363,7 +363,6 @@ static int register_trace_uprobe(struct trace_uprobe *tu) > static int create_trace_uprobe(int argc, char **argv) > { > struct trace_uprobe *tu; > - struct inode *inode; > char *arg, *event, *group, *filename; > char buf[MAX_EVENT_NAME_LEN]; > struct path path; > @@ -371,7 +370,6 @@ static int create_trace_uprobe(int argc, char **argv) > bool is_delete, is_return; > int i, ret; > > - inode = NULL; > ret = 0; > is_delete = false; > is_return = false; > @@ -437,24 +435,14 @@ static int create_trace_uprobe(int argc, char **argv) > } > /* Find the last occurrence, in case the path contains ':' too. */ > arg = strrchr(argv[1], ':'); > - if (!arg) { > - ret = -EINVAL; > - goto fail_address_parse; > - } > + if (!arg) > + return -EINVAL; > > *arg++ = '\0'; > filename = argv[1]; > ret = kern_path(filename, LOOKUP_FOLLOW, &path); > if (ret) > - goto fail_address_parse; > - > - inode = igrab(d_real_inode(path.dentry)); > - path_put(&path); > - > - if (!inode || !S_ISREG(inode->i_mode)) { > - ret = -EINVAL; > - goto fail_address_parse; > - } > + return ret; > > ret = kstrtoul(arg, 0, &offset); > if (ret) > @@ -490,7 +478,7 @@ static int create_trace_uprobe(int argc, char **argv) > goto fail_address_parse; > } > tu->offset = offset; > - tu->inode = inode; > + tu->path = path; > tu->filename = kstrdup(filename, GFP_KERNEL); > > if (!tu->filename) { > @@ -558,7 +546,7 @@ static int create_trace_uprobe(int argc, char **argv) > return ret; > > fail_address_parse: > - iput(inode); > + path_put(&path); > > pr_info("Failed to parse address or file.\n"); > > @@ -922,7 +910,8 @@ probe_event_enable(struct trace_uprobe *tu, struct > trace_event_file *file, > goto err_flags; > > tu->consumer.filter = filter; > - ret = uprobe_register(tu->inode, tu->offset, &tu->consumer); > + ret = uprobe_register(d_inode(tu->path.dentry), tu->offset, > + &tu->consumer); > if (ret) > goto err_buffer; > > @@ -966,7 +955,7 @@ probe_event_disable(struct trace_uprobe *tu, struct > trace_event_file *file) > > WARN_ON(!uprobe_filter_is_empty(&tu->filter)); > > - uprobe_unregister(tu->inode, tu->offset, &tu->consumer); > + uprobe_unregister(d_inode(tu->path.dentry), tu->offset, &tu->consumer); > tu->tp.flags &= file ? ~TP_FLAG_TRACE : ~TP_FLAG_PROFILE; > > uprobe_buffer_disable(); > @@ -1041,7 +1030,8 @@ static int uprobe_perf_close(struct trace_uprobe *tu, > struct perf_event *event) > write_unlock(&tu->filter.rwlock); > > if (!done) > - return uprobe_apply(tu->inode, tu->offset, &tu->consumer, > false); > + return uprobe_apply(d_inode(tu->path.dentry), tu->offset, > + &tu->consumer, false); > > return 0; > } > @@ -1073,7 +1063,8 @@ static int uprobe_perf_open(struct trace_uprobe *tu, > struct perf_event *event) > > err = 0; > if (!done) { > - err = uprobe_apply(tu->inode, tu->offset, &tu->consumer, true); > + err = uprobe_apply(d_inode(tu->path.dentry), > + tu->offset, &tu->consumer, true); > if (err) > uprobe_perf_close(tu, event); > } > @@ -1337,7 +1328,6 @@ struct trace_event_call * > create_local_trace_uprobe(char *name, unsigned long offs, bool is_return) > { > struct trace_uprobe *tu; > - struct inode *inode; > struct path path; > int ret; > > @@ -1345,14 +1335,6 @@ create_local_trace_uprobe(char *name, unsigned long > offs, bool is_return) > if (ret) > return ERR_PTR(ret); > > - inode = igrab(d_inode(path.dentry)); > - path_put(&path); > - > - if (!inode || !S_ISREG(inode->i_mode)) { > - iput(inode); > - return ERR_PTR(-EINVAL); > - } > - > /* > * local trace_kprobes are not added to probe_list, so they are never > * searched in find_trace_kprobe(). Therefore, there is no concern of > @@ -1364,11 +1346,12 @@ create_local_trace_uprobe(char *name, unsigned long > offs, bool is_return) > if (IS_ERR(tu)) { > pr_info("Failed to allocate trace_uprobe.(%d)\n", > (int)PTR_ERR(tu)); > + path_put(&path); > return ERR_CAST(tu); > } > > tu->offset = offs; > - tu->inode = inode; > + tu->path = path; > tu->filename = kstrdup(name, GFP_KERNEL); > init_trace_event_call(tu, &tu->tp.call); >
