Hi Roland!
> > > spin_lock_irqsave(&ehca_cq_idr_lock, flags);
> > > while (my_cq->nr_callbacks)
> > > yield();
>
> > Isn't that code outright buggy? Calling into the scheduler with a
> > spinlock held and local interrupts disabled...
>
> Yes, absolutely -- if nr_callbacks is ever nonzero then this will
> obviously crash instantly.
As Christoph R. mentioned in another thread I'm sending you a patch
to fix this bug. Thanks to all for this hint!
Purpose of the while loop is to wait until all completion entries
have been processed by a running completion handler. First then
the function continue with destroying completion queue. Thus, we do
unlock and lock around yield(), ie yield() is now called from a normal
process context without active lock. Hope that this pattern is ok.
In addition of yield issue this patch also fixes an unproper use of
spin_unlock() in ehca_irq.c.
Thanks
Nam
Signed-off-by Hoang-Nam Nguyen <[email protected]>
---
ehca_cq.c | 5 ++++-
ehca_irq.c | 4 +++-
2 files changed, 7 insertions(+), 2 deletions(-)
diff -Nurp infiniband_orig/drivers/infiniband/hw/ehca/ehca_cq.c infiniband_work/drivers/infiniband/hw/ehca/ehca_cq.c
--- infiniband_orig/drivers/infiniband/hw/ehca/ehca_cq.c 2007-01-11 19:54:06.000000000 +0100
+++ infiniband_work/drivers/infiniband/hw/ehca/ehca_cq.c 2007-01-12 15:27:50.000000000 +0100
@@ -330,8 +330,11 @@ int ehca_destroy_cq(struct ib_cq *cq)
}
spin_lock_irqsave(&ehca_cq_idr_lock, flags);
- while (my_cq->nr_callbacks)
+ while (my_cq->nr_callbacks) {
+ spin_unlock_irqrestore(&ehca_cq_idr_lock, flags);
yield();
+ spin_lock_irqsave(&ehca_cq_idr_lock, flags);
+ }
idr_remove(&ehca_cq_idr, my_cq->token);
spin_unlock_irqrestore(&ehca_cq_idr_lock, flags);
diff -Nurp infiniband_orig/drivers/infiniband/hw/ehca/ehca_irq.c infiniband_work/drivers/infiniband/hw/ehca/ehca_irq.c
--- infiniband_orig/drivers/infiniband/hw/ehca/ehca_irq.c 2007-01-11 19:53:33.000000000 +0100
+++ infiniband_work/drivers/infiniband/hw/ehca/ehca_irq.c 2007-01-12 15:27:50.000000000 +0100
@@ -440,7 +440,9 @@ void ehca_tasklet_eq(unsigned long data)
cq = idr_find(&ehca_cq_idr, token);
if (cq == NULL) {
- spin_unlock(&ehca_cq_idr_lock);
+ spin_unlock_irqrestore(
+ &ehca_cq_idr_lock,
+ flags);
break;
}
-
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