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authorAdam Litke <agl@us.ibm.com>2009-12-10 16:35:15 -0600
committerRusty Russell <rusty@rustcorp.com.au>2010-02-24 14:22:14 +1030
commit1f34c71afe5115e77a49c4e67720a66e27053e54 (patch)
treef6481c9a5fbafffd2bd8cbf17274fdc75ffc94b7 /drivers/scsi/esp_scsi.h
parent9564e138b1f6eb137f7149772438d3f3fb3277dd (diff)
virtio: Fix scheduling while atomic in virtio_balloon stats
This is a fix for my earlier patch: "virtio: Add memory statistics reporting to the balloon driver (V4)". I discovered that all_vm_events() can sleep and therefore stats collection cannot be done in interrupt context. One solution is to handle the interrupt by noting that stats need to be collected and waking the existing vballoon kthread which will complete the work via stats_handle_request(). Rusty, is this a saner way of doing business? There is one issue that I would like a broader opinion on. In stats_request, I update vb->need_stats_update and then wake up the kthread. The kthread uses vb->need_stats_update as a condition variable. Do I need a memory barrier between the update and wake_up to ensure that my kthread sees the correct value? My testing suggests that it is not needed but I would like some confirmation from the experts. Signed-off-by: Adam Litke <agl@us.ibm.com> To: Rusty Russell <rusty@rustcorp.com.au> Cc: Anthony Liguori <aliguori@linux.vnet.ibm.com> Cc: linux-kernel@vger.kernel.org Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'drivers/scsi/esp_scsi.h')
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