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From ae91e3d552aff4f0e74662d055dae06ea55eb6bc Mon Sep 17 00:00:00 2001
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From: "Frank Ch. Eigler" <fche@redhat.com>
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Date: Thu, 27 Mar 2014 21:29:04 -0400
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Subject: [PATCH] PR16766: kernel crash for failed-init module-notification
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Suppress the module_notifier callback for cases of failure of the
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main generated systemtap module-initialization code, which checks
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build-ids, privileges, etc. etc.; we don't want any module-notifier
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callbacks after an error.
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* runtime/transport/transport.c: Don't call module-notifier stuff
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if initialization failed.
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* translate.cxx (emit_module_refresh): Emit code to suppress callback
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payload if somehow the notifier got activated anyway.
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---
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runtime/transport/transport.c | 20 ++++++++++++--------
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translate.cxx | 11 +++++++++++
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2 files changed, 23 insertions(+), 8 deletions(-)
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diff --git a/runtime/transport/transport.c b/runtime/transport/transport.c
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index 1800764..e4d4d8e 100644
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--- a/runtime/transport/transport.c
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+++ b/runtime/transport/transport.c
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@@ -135,16 +135,20 @@ static void _stp_handle_start(struct _stp_msg_start *st)
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_stp_target = st->target;
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st->res = systemtap_module_init();
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- if (st->res == 0)
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+ if (st->res == 0) {
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_stp_probes_started = 1;
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- /* Register the module notifier. */
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- if (!_stp_module_notifier_active) {
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- int rc = register_module_notifier(& _stp_module_notifier_nb);
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- if (rc == 0)
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- _stp_module_notifier_active = 1;
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- else
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- _stp_warn ("Cannot register module notifier (%d)\n", rc);
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+ /* Register the module notifier ... */
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+ /* NB: but not if the module_init stuff
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+ failed: something nasty has happened, and
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+ we want no further probing started. PR16766 */
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+ if (!_stp_module_notifier_active) {
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+ int rc = register_module_notifier(& _stp_module_notifier_nb);
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+ if (rc == 0)
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+ _stp_module_notifier_active = 1;
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+ else
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+ _stp_warn ("Cannot register module notifier (%d)\n", rc);
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+ }
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}
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/* Called from the user context in response to a proc
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diff --git a/translate.cxx b/translate.cxx
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index 9903751..17dedd4 100644
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--- a/translate.cxx
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+++ b/translate.cxx
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@@ -1881,8 +1881,19 @@ c_unparser::emit_module_refresh ()
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{
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o->newline() << "static void systemtap_module_refresh (void) {";
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o->newline(1) << "int i=0, j=0;"; // for derived_probe_group use
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+
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+ /* If we're not in STARTING/RUNNING state, don't try doing any work.
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+ PR16766 */
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+ o->newline() << "int state = atomic_read (session_state());";
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+ o->newline() << "if (state != STAP_SESSION_RUNNING && state != STAP_SESSION_STARTING) {";
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+ // cannot _stp_warn etc. since we're not in probe context
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+ o->newline(1) << "printk (KERN_ERR \"stap module notifier triggered in unexpected state %d\", state);";
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+ o->newline() << "return;";
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+ o->newline(-1) << "}";
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+
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o->newline() << "(void) i;";
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o->newline() << "(void) j;";
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+
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vector<derived_probe_group*> g = all_session_groups (*session);
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for (unsigned i=0; i
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{
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--
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1.8.3.1
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