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CAPI: Rework application locking

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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>
This commit is contained in:
Jan Kiszka
2010-02-08 10:12:15 +00:00
committed by David S. Miller
parent 0ca3a017a7
commit 88c896ef87
2 changed files with 30 additions and 35 deletions
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11
drivers/isdn/capi/kcapi_proc.c
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@@ -139,9 +139,11 @@ static const struct file_operations proc_contrstats_ops = {
// 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 @@ applications_next(struct seq_file *seq, void *v, loff_t *pos)
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