[PATCH v3] um: net: replace GFP_KERNEL with GFP_ATOMIC when spinlock is held

Saurabh Sengar
2015-10-29T09:16:54Z

replace GFP_KERNEL with GFP_ATOMIC while spinlock is held,
as code while holding a spinlock should be atomic.
GFP_KERNEL may sleep and can cause deadlock,
where as GFP_ATOMIC may fail but certainly avoids deadlock

Signed-off-by: Saurabh Sengar <saurabh.truth@gmail.com>
---
v3: removed the atomic variable, as per Richard comment

arch/um/drivers/net_kern.c | 21 +++++++++++++--------
1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/arch/um/drivers/net_kern.c b/arch/um/drivers/net_kern.c
index f70dd54..d898f6c 100644
--- a/arch/um/drivers/net_kern.c
+++ b/arch/um/drivers/net_kern.c
@@ -388,7 +388,7 @@ static const struct net_device_ops uml_netdev_ops = {
static int driver_registered;

static void eth_configure(int n, void *init, char *mac,
- struct transport *transport)
+ struct transport *transport, int gfp_mask)
{
struct uml_net *device;
struct net_device *dev;
@@ -397,7 +397,7 @@ static void eth_configure(int n, void *init, char *mac,

size = transport->private_size + sizeof(struct uml_net_private);

- device = kzalloc(sizeof(*device), GFP_KERNEL);
+ device = kzalloc(sizeof(*device), gfp_mask);
if (device == NULL) {
printk(KERN_ERR "eth_configure failed to allocate struct "
"uml_net\n");
@@ -568,7 +568,7 @@ static LIST_HEAD(transports);
static LIST_HEAD(eth_cmd_line);

static int check_transport(struct transport *transport, char *eth, int n,
- void **init_out, char **mac_out)
+ void **init_out, char **mac_out, int gfp_mask)
{
int len;

@@ -582,7 +582,7 @@ static int check_transport(struct transport *transport, char *eth, int n,
else if (*eth != '\0')
return 0;

- *init_out = kmalloc(transport->setup_size, GFP_KERNEL);
+ *init_out = kmalloc(transport->setup_size, gfp_mask);
if (*init_out == NULL)
return 1;

@@ -600,20 +600,22 @@ void register_transport(struct transport *new)
void *init;
char *mac = NULL;
int match;
+ int gfp_mask;

spin_lock(&transports_lock);
BUG_ON(!list_empty(&new->list));
list_add(&new->list, &transports);
spin_unlock(&transports_lock);

+ gfp_mask = GFP_KERNEL;
list_for_each_safe(ele, next, &eth_cmd_line) {
eth = list_entry(ele, struct eth_init, list);
match = check_transport(new, eth->init, eth->index, &init,
- &mac);
+ &mac, gfp_mask);
if (!match)
continue;
else if (init != NULL) {
- eth_configure(eth->index, init, mac, new);
+ eth_configure(eth->index, init, mac, new, gfp_mask);
kfree(init);
}
list_del(&eth->list);
@@ -627,14 +629,17 @@ static int eth_setup_common(char *str, int index)
void *init;
char *mac = NULL;
int found = 0;
+ int gfp_mask;

spin_lock(&transports_lock);
+ gfp_mask = GFP_ATOMIC;
list_for_each(ele, &transports) {
transport = list_entry(ele, struct transport, list);
- if (!check_transport(transport, str, index, &init, &mac))
+ if (!check_transport(transport, str, index, &init,
+ &mac, gfp_mask))
continue;
if (init != NULL) {
- eth_configure(index, init, mac, transport);
+ eth_configure(index, init, mac, transport, gfp_mask);
kfree(init);
}
found = 1;
--
1.9.1