Messages in this thread Patch in this message | | | From | Hoang-Nam Nguyen <> | Subject | Re: [PATCH/RFC 2.6.21 3/5] ehca: completion queue: remove use of do_mmap() | Date | Fri, 12 Jan 2007 16:23:13 +0100 |
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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 <hnguyen@de.ibm.com> ---
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; } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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