[PATCH] arm/mach-at91/pm: Do not double put the device node

On 2018/8/16 17:32, Claudiu Beznea wrote:

Hi Alexandre,

On 14.08.2018 15:59, Alexandre Belloni wrote:

quoted

On 14/08/2018 09:54:56+0800, zhong jiang wrote:

quoted

Device node iterators put the previous value of the index variable,
so an explicit put causes a double put.

While for_each_matching_node_and_match will get and put the node
properly, there is also a call to of_find_device_by_node that will get a
reference to the node.

Looking through of_find_device_by_node() it seems that a put_device() on the
struct device member of the returned struct platform_device has to be called
instead of of_node_put().

of_find_device_by_node() calls bus_find_device():

dev = bus_find_device(&platform_bus_type, NULL, np, of_dev_node_match); 

the match function, of_dev_node_match(), is just as follows:

static int of_dev_node_match(struct device *dev, void *data)                    
{                                                                               
        return dev->of_node == data;                                            
}                                                                               

but bus_find_device() takes a reference to the struct device returned in case it
founds a match, via get_device():

struct device *bus_find_device(struct bus_type *bus,                            
                               struct device *start, void *data,                
                               int (*match)(struct device *dev,
			       void*data))    
{                                                                               
        struct klist_iter i;                                                    
        struct device *dev;                                                     
                                                                                
        if (!bus || !bus->p)                                                    
                return NULL;                                                    
                                                                                
        klist_iter_init_node(&bus->p->klist_devices, &i,                        
                             (start ? &start->p->knode_bus : NULL));            
        while ((dev = next_device(&i)))                                         
                if (match(dev, data) && get_device(dev))                        
                        break;                                                  
        klist_iter_exit(&i);                                                    
        return dev;                                                             
}                                                                               

So, I think a put_device(&pdev->dev) has to be called in at91_pm_config_ws()
instead of of_node_put(np). My bad!

Yes, you're right. Thanks, Claudiu. I will repost in v2.

Sincerely,
zhong jiang

Thank you,
Claudiu Beznea

quoted

quoted

I detect the issue with the help of Coccinelle.

Signed-off-by: zhong jiang <redacted>
---
 arch/arm/mach-at91/pm.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c
index 32fae4d..a5ec35f 100644
--- a/arch/arm/mach-at91/pm.c
+++ b/arch/arm/mach-at91/pm.c

@@ -143,15 +143,12 @@ static int at91_pm_config_ws(unsigned int pm_mode, bool set)
 
 			/* Check if enabled on SHDWC. */
 			if (wsi->shdwc_mr_bit && !(val & wsi->shdwc_mr_bit))
-				goto put_node;
+				continue;
 
 			mode |= wsi->pmc_fsmr_bit;
 			if (wsi->set_polarity)
 				polarity |= wsi->pmc_fsmr_bit;
 		}
-
-put_node:
-		of_node_put(np);
 	}
 
 	if (mode) {

-- 
1.7.12.4

.