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staging: unisys: visorchannel: Add peek function

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According to unisys, the s_par hypervisor has a bug in which it never
triggers an interrupt.  That makes the visornic effectively a 2ms poll
loop.  In order to just have the rx thread shceduling a napi poll every
2ms, lets instead give it the chance to check the response queue for
data before we schedule.  This helper provides that functionality

Signed-off-by: Neil Horman <nhorman@redhat.com>
Signed-off-by: Benjamin Romer <benjamin.romer@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Neil Horman 2015-07-31 18:56:32 -04:00 committed by Greg Kroah-Hartman
parent fd93b80592
commit fdc792cd1b
2 changed files with 23 additions and 0 deletions
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2
drivers/staging/unisys/include/visorbus.h
View File

@ -201,6 +201,8 @@ bool visorchannel_signalremove(struct visorchannel *channel, u32 queue,
void *msg);
bool visorchannel_signalinsert(struct visorchannel *channel, u32 queue,
void *msg);
bool visorchannel_signalempty(struct visorchannel *channel, u32 queue);
int visorchannel_signalqueue_slots_avail(struct visorchannel *channel,
u32 queue);
int visorchannel_signalqueue_max_slots(struct visorchannel *channel, u32 queue);

21
drivers/staging/unisys/visorbus/visorchannel.c
View File

@ -430,6 +430,27 @@ visorchannel_signalremove(struct visorchannel *channel, u32 queue, void *msg)
}
EXPORT_SYMBOL_GPL(visorchannel_signalremove);
bool
visorchannel_signalempty(struct visorchannel *channel, u32 queue)
{
unsigned long flags = 0;
struct signal_queue_header sig_hdr;
bool rc = false;
if (channel->needs_lock)
spin_lock_irqsave(&channel->remove_lock, flags);
if (!sig_read_header(channel, queue, &sig_hdr))
rc = true;
if (sig_hdr.head == sig_hdr.tail)
rc = true;
if (channel->needs_lock)
spin_unlock_irqrestore(&channel->remove_lock, flags);
return rc;
}
EXPORT_SYMBOL_GPL(visorchannel_signalempty);
static bool
signalinsert_inner(struct visorchannel *channel, u32 queue, void *msg)
{