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NVMe: Call put_nvmeq() before calling nvme_submit_sync_cmd()

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We can't have preemption disabled when we call schedule().  Accept the
possibility that we'll get preempted, and it'll cost us some cacheline
bounces.

Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
This commit is contained in:
Matthew Wilcox 2011-02-04 16:14:30 -05:00
parent 3c0cf138d7
commit b1ad37efca
1 changed files with 6 additions and 1 deletions
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7
drivers/block/nvme.c
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@ -842,8 +842,13 @@ static int nvme_submit_io(struct nvme_ns *ns, struct nvme_user_io __user *uio)
nvme_setup_prps(&c.common, sg, length);
nvmeq = get_nvmeq(ns);
status = nvme_submit_sync_cmd(nvmeq, &c, &result);
/* Since nvme_submit_sync_cmd sleeps, we can't keep preemption
* disabled. We may be preempted at any point, and be rescheduled
* to a different CPU. That will cause cacheline bouncing, but no
* additional races since q_lock already protects against other CPUs.
*/
put_nvmeq(nvmeq);
status = nvme_submit_sync_cmd(nvmeq, &c, &result);
nvme_unmap_user_pages(dev, io.opcode & 1, io.addr, length, sg, nents);
put_user(result, &uio->result);