CAPI: Rework application locking
Drop the application rw-lock in favour of RCU. This synchronizes
capi20_release against capi_ctr_handle_message which may dereference an
application from (soft-)IRQ context. Any other access to the application
list is now protected by the capi_controller_lock as well. This also
allows to safely inspect applications for /proc dumping by holding
capi_controller_lock.
At this chance, drop some useless release_in_progress checks where we
obtained the application pointer from the list (which becomes NULL on
release_in_progress).
Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/isdn/capi/kcapi_proc.c b/drivers/isdn/capi/kcapi_proc.c
index 3e6e17a..ea2dff6 100644
--- a/drivers/isdn/capi/kcapi_proc.c
+++ b/drivers/isdn/capi/kcapi_proc.c
@@ -139,9 +139,11 @@
// applid nrecvctlpkt nrecvdatapkt nsentctlpkt nsentdatapkt
// ---------------------------------------------------------------------------
-static void *
-applications_start(struct seq_file *seq, loff_t *pos)
+static void *applications_start(struct seq_file *seq, loff_t *pos)
+ __acquires(capi_controller_lock)
{
+ mutex_lock(&capi_controller_lock);
+
if (*pos < CAPI_MAXAPPL)
return &capi_applications[*pos];
@@ -158,9 +160,10 @@
return NULL;
}
-static void
-applications_stop(struct seq_file *seq, void *v)
+static void applications_stop(struct seq_file *seq, void *v)
+ __releases(capi_controller_lock)
{
+ mutex_unlock(&capi_controller_lock);
}
static int