I''m not sure how I didn''t spot this sooner, but some of the
code I wrote
for netfront acceleration was calling kmalloc(GFP_KERNEL) with a spin
lock held, and so irqs disabled, which is bad. This patch fixes it by
making it a bit less eager to hold the spin lock.
Signed-off-by Kieran Mansley <kmansley@solarflare.com>
Over-eager locking meant kmalloc at GFP_KERNEL with irqs disabled
diff -r b65a76ffb4bb drivers/xen/netfront/accel.c
--- a/drivers/xen/netfront/accel.c Tue Dec 18 13:11:39 2007 +0000
+++ b/drivers/xen/netfront/accel.c Thu Dec 20 11:21:09 2007 +0000
@@ -273,6 +273,7 @@ static int init_accelerator(const char *
{
struct netfront_accelerator *accelerator =
kmalloc(sizeof(struct netfront_accelerator), GFP_KERNEL);
+ unsigned long flags;
int frontend_len;
if (!accelerator) {
@@ -294,7 +295,9 @@ static int init_accelerator(const char *
accelerator->hooks = hooks;
+ spin_lock_irqsave(&accelerators_lock, flags);
list_add(&accelerator->link, &accelerators_list);
+ spin_unlock_irqrestore(&accelerators_lock, flags);
*result = accelerator;
@@ -365,11 +368,8 @@ static int netfront_load_accelerator(str
{
struct netfront_accelerator *accelerator;
int rc = 0;
- unsigned long flags;
DPRINTK(" %s\n", frontend);
-
- spin_lock_irqsave(&accelerators_lock, flags);
/*
* Look at list of loaded accelerators to see if the requested
@@ -377,8 +377,6 @@ static int netfront_load_accelerator(str
*/
list_for_each_entry(accelerator, &accelerators_list, link) {
if (match_accelerator(frontend, accelerator)) {
- spin_unlock_irqrestore(&accelerators_lock, flags);
-
accelerator_probe_new_vif(np, dev, accelerator);
return 0;
}
@@ -386,11 +384,8 @@ static int netfront_load_accelerator(str
/* Couldn''t find it, so create a new one and load the module */
if ((rc = init_accelerator(frontend, &accelerator, NULL)) < 0) {
- spin_unlock_irqrestore(&accelerators_lock, flags);
return rc;
}
-
- spin_unlock_irqrestore(&accelerators_lock, flags);
/* Include this frontend device on the accelerator''s list */
add_accelerator_vif(accelerator, np);
@@ -450,7 +445,6 @@ int netfront_accelerator_loaded(int vers
struct netfront_accel_hooks *hooks)
{
struct netfront_accelerator *accelerator;
- unsigned long flags;
if (version != NETFRONT_ACCEL_VERSION) {
if (version > NETFRONT_ACCEL_VERSION) {
@@ -469,18 +463,13 @@ int netfront_accelerator_loaded(int vers
mutex_lock(&accelerator_mutex);
- spin_lock_irqsave(&accelerators_lock, flags);
-
/*
* Look through list of accelerators to see if it has already
* been requested
*/
list_for_each_entry(accelerator, &accelerators_list, link) {
if (match_accelerator(frontend, accelerator)) {
- spin_unlock_irqrestore(&accelerators_lock, flags);
-
accelerator_probe_vifs(accelerator, hooks);
-
goto out;
}
}
@@ -493,8 +482,6 @@ int netfront_accelerator_loaded(int vers
frontend);
init_accelerator(frontend, &accelerator, hooks);
-
- spin_unlock_irqrestore(&accelerators_lock, flags);
out:
mutex_unlock(&accelerator_mutex);
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