Messages in this thread Patch in this message | | | Date | Wed, 23 Apr 2014 18:58:30 +0200 | From | Oleg Nesterov <> | Subject | [PATCH 1/1] uprobes/tracing: uprobe_perf_open() forgets to handle the error from uprobe_apply() |
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uprobe_perf_open()->uprobe_apply() can fail, but this error is wrongly ignored. Change uprobe_perf_open() to do uprobe_perf_close() and return the error code in this case.
Change uprobe_perf_close() to propogate the error from uprobe_apply() as well, although it should not fail.
The patch looks more complicated because it moves uprobe_perf_close() up to make it visible to uprobe_perf_open().
Signed-off-by: Oleg Nesterov <oleg@redhat.com> --- kernel/trace/trace_uprobe.c | 46 +++++++++++++++++++++++------------------- 1 files changed, 25 insertions(+), 21 deletions(-)
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c index 930e514..9aad3e2 100644 --- a/kernel/trace/trace_uprobe.c +++ b/kernel/trace/trace_uprobe.c @@ -1003,56 +1003,60 @@ uprobe_filter_event(struct trace_uprobe *tu, struct perf_event *event) return __uprobe_perf_filter(&tu->filter, event->hw.tp_target->mm); } -static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event *event) +static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event *event) { bool done; write_lock(&tu->filter.rwlock); if (event->hw.tp_target) { - /* - * event->parent != NULL means copy_process(), we can avoid - * uprobe_apply(). current->mm must be probed and we can rely - * on dup_mmap() which preserves the already installed bp's. - * - * attr.enable_on_exec means that exec/mmap will install the - * breakpoints we need. - */ + list_del(&event->hw.tp_list); done = tu->filter.nr_systemwide || - event->parent || event->attr.enable_on_exec || + (event->hw.tp_target->flags & PF_EXITING) || uprobe_filter_event(tu, event); - list_add(&event->hw.tp_list, &tu->filter.perf_events); } else { + tu->filter.nr_systemwide--; done = tu->filter.nr_systemwide; - tu->filter.nr_systemwide++; } write_unlock(&tu->filter.rwlock); if (!done) - uprobe_apply(tu->inode, tu->offset, &tu->consumer, true); + return uprobe_apply(tu->inode, tu->offset, &tu->consumer, false); return 0; } -static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event *event) +static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event *event) { bool done; + int err; write_lock(&tu->filter.rwlock); if (event->hw.tp_target) { - list_del(&event->hw.tp_list); + /* + * event->parent != NULL means copy_process(), we can avoid + * uprobe_apply(). current->mm must be probed and we can rely + * on dup_mmap() which preserves the already installed bp's. + * + * attr.enable_on_exec means that exec/mmap will install the + * breakpoints we need. + */ done = tu->filter.nr_systemwide || - (event->hw.tp_target->flags & PF_EXITING) || + event->parent || event->attr.enable_on_exec || uprobe_filter_event(tu, event); + list_add(&event->hw.tp_list, &tu->filter.perf_events); } else { - tu->filter.nr_systemwide--; done = tu->filter.nr_systemwide; + tu->filter.nr_systemwide++; } write_unlock(&tu->filter.rwlock); - if (!done) - uprobe_apply(tu->inode, tu->offset, &tu->consumer, false); - - return 0; + err = 0; + if (!done) { + err = uprobe_apply(tu->inode, tu->offset, &tu->consumer, true); + if (err) + uprobe_perf_close(tu, event); + } + return err; } static bool uprobe_perf_filter(struct uprobe_consumer *uc, -- 1.5.5.1
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