From f0208b7155bc6e395c09652290a16b66e77442f3 Mon Sep 17 00:00:00 2001 From: Cathal Mullaney Date: Wed, 19 Oct 2016 22:43:25 +0100 Subject: [PATCH] staging: unisys: visorbus: visorchannel: Refactor locking code to be statically deterministic. This patch makes locking in visorchannel_signalempty statically deterministic. As a result this patch fixes the sparse warning: Context imbalance in 'visorchannel_signalempty' - different lock contexts for basic block. The logic of the locking code doesn't change but the layout of the original code is "frowned upon" according to mails on sparse context checking. Refactoring removes the warning and makes the code more readable. Signed-off-by: Cathal Mullaney Tested-by: David Kershner Signed-off-by: Greg Kroah-Hartman --- .../staging/unisys/visorbus/visorchannel.c | 30 ++++++++++++------- 1 file changed, 19 insertions(+), 11 deletions(-) diff --git a/drivers/staging/unisys/visorbus/visorchannel.c b/drivers/staging/unisys/visorbus/visorchannel.c index a1381eb81674..a41115733a50 100644 --- a/drivers/staging/unisys/visorbus/visorchannel.c +++ b/drivers/staging/unisys/visorbus/visorchannel.c @@ -300,22 +300,30 @@ EXPORT_SYMBOL_GPL(visorchannel_signalremove); * Return: boolean indicating whether any messages in the designated * channel/queue are present */ + +static bool +queue_empty(struct visorchannel *channel, u32 queue) +{ + struct signal_queue_header sig_hdr; + + if (sig_read_header(channel, queue, &sig_hdr)) + return true; + + return (sig_hdr.head == sig_hdr.tail); +} + bool visorchannel_signalempty(struct visorchannel *channel, u32 queue) { - unsigned long flags = 0; - struct signal_queue_header sig_hdr; - bool rc = false; + bool rc; + unsigned long flags; - if (channel->needs_lock) - spin_lock_irqsave(&channel->remove_lock, flags); + if (!channel->needs_lock) + return queue_empty(channel, queue); - 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); + spin_lock_irqsave(&channel->remove_lock, flags); + rc = queue_empty(channel, queue); + spin_unlock_irqrestore(&channel->remove_lock, flags); return rc; } -- 2.20.1