[PATCH 1/2] powerpc: Add spinlock to request_phb_iospace()

request_phb_iospace() can be called from different CPUs at init
time (at least with my next patch) and thus needs a spinlock. As
for the next patch, this is a temporary workaround for 2.6.22
issues until my rewrite of IO mappings is ready (for 2.6.23)

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

 arch/powerpc/mm/pgtable_64.c |    4 ++++
 1 file changed, 4 insertions(+)

Index: linux-cell/arch/powerpc/mm/pgtable_64.c
===================================================================

--- linux-cell.orig/arch/powerpc/mm/pgtable_64.c	2007-05-15 13:17:59.000000000 +1000
+++ linux-cell/arch/powerpc/mm/pgtable_64.c	2007-05-15 13:18:32.000000000 +1000

@@ -322,6 +322,8 @@ EXPORT_SYMBOL(__ioremap);
 EXPORT_SYMBOL(iounmap);
 EXPORT_SYMBOL(__iounmap);
 
+static DEFINE_SPINLOCK(phb_io_lock);
+
 void __iomem * reserve_phb_iospace(unsigned long size)
 {
 	void __iomem *virt_addr;

@@ -329,8 +331,10 @@ void __iomem * reserve_phb_iospace(unsig
 	if (phbs_io_bot >= IMALLOC_BASE) 
 		panic("reserve_phb_iospace(): phb io space overflow\n");
 			
+	spin_lock(&phb_io_lock);
 	virt_addr = (void __iomem *) phbs_io_bot;
 	phbs_io_bot += size;
+	spin_unlock(&phb_io_lock);
 
 	return virt_addr;
 }

On Tue, 15 May 2007 14:16:26 +1000 Benjamin Herrenschmidt [off-list ref] wrote:

request_phb_iospace() can be called from different CPUs at init
time (at least with my next patch) and thus needs a spinlock. As
for the next patch, this is a temporary workaround for 2.6.22
issues until my rewrite of IO mappings is ready (for 2.6.23)

What problem is this solving?

--
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au
http://www.canb.auug.org.au/~sfr/

On Tue, 2007-05-15 at 14:26 +1000, Stephen Rothwell wrote:

On Tue, 15 May 2007 14:16:26 +1000 Benjamin Herrenschmidt [off-list ref] wrote:

quoted

request_phb_iospace() can be called from different CPUs at init
time (at least with my next patch) and thus needs a spinlock. As
for the next patch, this is a temporary workaround for 2.6.22
issues until my rewrite of IO mappings is ready (for 2.6.23)

What problem is this solving?

See the description of the next patch.

Ben.