[dm-devel] [PATCH 1/2] multipathd: register threads that use rcu calls

[Benjamin Marzinski]

All calls to condlog() are rcu reader side calls, so any thread that
uses condlog() must register itself. The only threads that are exempt
are log_thread, since it never calls condlog (or any other function that
calls get_multipath_config) and mpath_pr_event_handler_fn, which is only
called by mpath_persist, which disables the rcu handling.

Signed-off-by: Benjamin Marzinski <bmarz...@redhat.com>
---
 libmultipath/checkers/rbd.c | 7 +++++--
 libmultipath/checkers/tur.c | 9 ++++++---
 multipathd/main.c           | 7 +++++--
 3 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/libmultipath/checkers/rbd.c b/libmultipath/checkers/rbd.c
index b1d99b4..4ff54f4 100644
--- a/libmultipath/checkers/rbd.c
+++ b/libmultipath/checkers/rbd.c
@@ -19,6 +19,7 @@
 #include <sys/ioctl.h>
 #include <sys/time.h>
 #include <sys/wait.h>
+#include <urcu.h>
 
 #include "rados/librados.h"
 
@@ -517,6 +518,7 @@ static void cleanup_func(void *data)
        pthread_spin_unlock(&ct->hldr_lock);
        if (!holders)
                cleanup_context(ct);
+       rcu_unregister_thread();
 }
 
 static void *rbd_thread(void *ctx)
@@ -524,11 +526,12 @@ static void *rbd_thread(void *ctx)
        struct rbd_checker_context *ct = ctx;
        int state;
 
+       /* This thread can be canceled, so setup clean up */
+       rbd_thread_cleanup_push(ct)
+       rcu_register_thread();
        condlog(3, "rbd%d: thread starting up", ct->rbd_bus_id);
 
        ct->message[0] = '\0';
-       /* This thread can be canceled, so setup clean up */
-       rbd_thread_cleanup_push(ct)
 
        /* checker start up */
        pthread_mutex_lock(&ct->lock);
diff --git a/libmultipath/checkers/tur.c b/libmultipath/checkers/tur.c
index 9155960..eb3348d 100644
--- a/libmultipath/checkers/tur.c
+++ b/libmultipath/checkers/tur.c
@@ -15,6 +15,7 @@
 #include <errno.h>
 #include <sys/time.h>
 #include <pthread.h>
+#include <urcu.h>
 #include <urcu/uatomic.h>
 
 #include "checkers.h"
@@ -220,6 +221,7 @@ static void cleanup_func(void *data)
        holders = uatomic_sub_return(&ct->holders, 1);
        if (!holders)
                cleanup_context(ct);
+       rcu_unregister_thread();
 }
 
 static void copy_msg_to_tcc(void *ct_p, const char *msg)
@@ -237,11 +239,12 @@ static void *tur_thread(void *ctx)
        int state, running;
        char devt[32];
 
-       condlog(3, "%s: tur checker starting up",
-               tur_devt(devt, sizeof(devt), ct));
-
        /* This thread can be canceled, so setup clean up */
        tur_thread_cleanup_push(ct);
+       rcu_register_thread();
+
+       condlog(3, "%s: tur checker starting up",
+               tur_devt(devt, sizeof(devt), ct));
 
        /* TUR checker start up */
        pthread_mutex_lock(&ct->lock);
diff --git a/multipathd/main.c b/multipathd/main.c
index 3ae0442..eccb046 100644
--- a/multipathd/main.c
+++ b/multipathd/main.c
@@ -3041,12 +3041,13 @@ void *  mpath_pr_event_handler_fn (void * pathp )
        struct prout_param_descriptor *param;
        struct prin_resp *resp;
 
+       rcu_register_thread();
        mpp = pp->mpp;
 
        resp = mpath_alloc_prin_response(MPATH_PRIN_RKEY_SA);
        if (!resp){
                condlog(0,"%s Alloc failed for prin response", pp->dev);
-               return NULL;
+               goto out;
        }
 
        ret = prin_do_scsi_ioctl(pp->dev, MPATH_PRIN_RKEY_SA, resp, 0);
@@ -3104,7 +3105,9 @@ void *  mpath_pr_event_handler_fn (void * pathp )
 
        free(param);
 out:
-       free(resp);
+       if (resp)
+               free(resp);
+       rcu_unregister_thread();
        return NULL;
 }
 
-- 
2.7.4

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