On 09/16/2010 09:31 PM, Nicholas A. Bellinger wrote:
On Thu, 2010-09-16 at 18:29 -0700, Tim Chen wrote:
On Thu, 2010-09-16 at 15:35 -0700, Nicholas A. Bellinger wrote:
From: Nicholas Bellinger<nab@xxxxxxxxxxxxxxx>
Greetings all,
This series contains the first round of a whole-sale conversion for droping
struct Scsi_Host->host_lock around struct Scsi_Host->queuecommand() within
scsi_dispatch_cmd(). So with this first patch the only part of scsi_dispatch_cmd()
that is protected by host_lock is scsi_cmd_get_serial)_.
Maybe we can change the host->cmd_serial_number to atomic and totally
avoid the need to take host_lock.
Hmmmm good point, then we would also need an atomic_t for signaling
(shost_state == SHOST_DEL) in scsi_dispatch_cmd() to be able to
completly drop host_lock usage within scsi_dispatch_cmd().
I can take a look at doing this specific part, if you would be willing
to have a look at the host->cmd_serial_number conversion piece. ;)
But that raises the familiar tale of: using multiple atomics (w/ their
locked instructions) may cost more than a spinlock.
Jeff
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