From sgruszka@redhat.com Mon Jan 17 08:03:52 2011
From: Stanislaw Gruszka <sgruszka@redhat.com>
To: stable@kernel.org, kernel@lists.fedoraproject.org
Subject: [PATCH 2.6.35.y] hostap_cs: fix sleeping function called from invalid context
Date: Mon, 17 Jan 2011 14:03:36 +0100
Message-Id: <1295269416-4870-1-git-send-email-sgruszka@redhat.com>

commit 4e5518ca53be29c1ec3c00089c97bef36bfed515 upstream.

pcmcia_request_irq() and pcmcia_enable_device() are intended
to be called from process context (first function allocate memory
with GFP_KERNEL, second take a mutex). We can not take spin lock
and call them.

It's safe to move spin lock after pcmcia_enable_device() as we
still hold off IRQ until dev->base_addr is 0 and driver will
not proceed with interrupts when is not ready.

Patch resolves:
https://bugzilla.redhat.com/show_bug.cgi?id=643758

Reported-and-tested-by: rbugz@biobind.com
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
---
 drivers/net/wireless/hostap/hostap_cs.c |   15 ++++++---------
 1 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/drivers/net/wireless/hostap/hostap_cs.c b/drivers/net/wireless/hostap/hostap_cs.c
index 29b31a6..4ebf63d 100644
--- a/drivers/net/wireless/hostap/hostap_cs.c
+++ b/drivers/net/wireless/hostap/hostap_cs.c
@@ -627,14 +627,13 @@ static int prism2_config(struct pcmcia_device *link)
 	hw_priv->link = link;
 
 	/*
-	 * Make sure the IRQ handler cannot proceed until at least
-	 * dev->base_addr is initialized.
+	 * We enable IRQ here, but IRQ handler will not proceed
+	 * until dev->base_addr is set below. This protect us from
+	 * receive interrupts when driver is not initialized.
 	 */
-	spin_lock_irqsave(&local->irq_init_lock, flags);
-
 	ret = pcmcia_request_irq(link, prism2_interrupt);
 	if (ret)
-		goto failed_unlock;
+		goto failed;
 
 	/*
 	 * This actually configures the PCMCIA socket -- setting up
@@ -643,11 +642,11 @@ static int prism2_config(struct pcmcia_device *link)
 	 */
 	ret = pcmcia_request_configuration(link, &link->conf);
 	if (ret)
-		goto failed_unlock;
+		goto failed;
 
+	spin_lock_irqsave(&local->irq_init_lock, flags);
 	dev->irq = link->irq;
 	dev->base_addr = link->io.BasePort1;
-
 	spin_unlock_irqrestore(&local->irq_init_lock, flags);
 
 	/* Finally, report what we've done */
@@ -676,8 +675,6 @@ static int prism2_config(struct pcmcia_device *link)
 
 	return ret;
 
- failed_unlock:
-	 spin_unlock_irqrestore(&local->irq_init_lock, flags);
  failed:
 	kfree(hw_priv);
 	prism2_release((u_long)link);
-- 
1.7.1