Messages in this thread Patch in this message | | | Date | Mon, 21 Sep 2009 21:35:47 +0200 (CEST) | From | John Kacur <> | Subject | [PATCH] ib-release-locks-in-the-proper-order |
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Please consider the following patch - originally from Steven Rostedt. It solves a problem for rt which is very sensitive to the lock ordering. It should have a no impact on non-rt.
The patch applies to current tip/master - but it is fine with me if it would be more appropriate for one of the infiniband people to take it.
Thanks
From e533f2b9ee9b0bd95aaa4c3369e79b350c9895d3 Mon Sep 17 00:00:00 2001 From: Steven Rostedt <srostedt@redhat.com> Date: Mon, 21 Sep 2009 21:23:46 +0200 Subject: [PATCH] ib: release locks in the proper order
RT is very sensitive to the order locks are taken and released wrt read write locks. We must do
lock(a); lock(b); lock(c);
[...]
unlock(c); unlock(b); unlock(a);
otherwise bad things can happen.
Signed-off-by: Ken Cox <jkc@redhat.com> Signed-off-by: Clark Williams <williams@redhat.com> Signed-off-by: John Kacur <jkacur@redhat.com> --- drivers/infiniband/core/uverbs_cmd.c | 20 ++++++++++---------- 1 files changed, 10 insertions(+), 10 deletions(-)
diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c index 56feab6..5ea66e1 100644 --- a/drivers/infiniband/core/uverbs_cmd.c +++ b/drivers/infiniband/core/uverbs_cmd.c @@ -1116,12 +1116,12 @@ ssize_t ib_uverbs_create_qp(struct ib_uverbs_file *file, goto err_copy; } - put_pd_read(pd); - put_cq_read(scq); - if (rcq != scq) - put_cq_read(rcq); if (srq) put_srq_read(srq); + if (rcq != scq) + put_cq_read(rcq); + put_cq_read(scq); + put_pd_read(pd); mutex_lock(&file->mutex); list_add_tail(&obj->uevent.uobject.list, &file->ucontext->qp_list); @@ -1140,14 +1140,14 @@ err_destroy: ib_destroy_qp(qp); err_put: - if (pd) - put_pd_read(pd); - if (scq) - put_cq_read(scq); - if (rcq && rcq != scq) - put_cq_read(rcq); if (srq) put_srq_read(srq); + if (rcq && rcq != scq) + put_cq_read(rcq); + if (scq) + put_cq_read(scq); + if (pd) + put_pd_read(pd); put_uobj_write(&obj->uevent.uobject); return ret; -- 1.6.0.6
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