Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=a0a46196cd98af5cc015842bba757571f02a8c30
Commit: a0a46196cd98af5cc015842bba757571f02a8c30
Parent: bdb95b1792664f25eb2a4d13a587d2020aa93002
Author: David S. Miller <[EMAIL PROTECTED]>
AuthorDate: Mon Jan 7 20:35:07 2008 -0800
Committer: David S. Miller <[EMAIL PROTECTED]>
CommitDate: Tue Jan 8 23:30:07 2008 -0800
[NET]: Add NAPI_STATE_DISABLE.
Create a bit to signal that a napi_disable() is in progress.
This sets up infrastructure such that net_rx_action() can generically
break out of the ->poll() loop on a NAPI context that has a pending
napi_disable() yet is being bombed with packets (and thus would
otherwise poll endlessly and not allow the napi_disable() to finish).
Now, what napi_disable() does is first set the NAPI_STATE_DISABLE bit
(to indicate that a disable is pending), then it polls for the
NAPI_STATE_SCHED bit, and once the NAPI_STATE_SCHED bit is acquired
the NAPI_STATE_DISABLE bit is cleared. Here, the test_and_set_bit()
provides the necessary memory barrier between the various bitops.
napi_schedule_prep() now tests for a pending disable as it's first
action and won't try to obtain the NAPI_STATE_SCHED bit if a disable
is pending.
As a result, we can remove the netif_running() check in
netif_rx_schedule_prep() because the NAPI disable pending state serves
this purpose. And, it does so in a NAPI centric manner which is what
we really want.
Signed-off-by: David S. Miller <[EMAIL PROTECTED]>
---
include/linux/netdevice.h | 16 +++++++++++++---
1 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index e393995..b0813c3 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -319,21 +319,29 @@ struct napi_struct {
enum
{
NAPI_STATE_SCHED, /* Poll is scheduled */
+ NAPI_STATE_DISABLE, /* Disable pending */
};
extern void FASTCALL(__napi_schedule(struct napi_struct *n));
+static inline int napi_disable_pending(struct napi_struct *n)
+{
+ return test_bit(NAPI_STATE_DISABLE, &n->state);
+}
+
/**
* napi_schedule_prep - check if napi can be scheduled
* @n: napi context
*
* Test if NAPI routine is already running, and if not mark
* it as running. This is used as a condition variable
- * insure only one NAPI poll instance runs
+ * insure only one NAPI poll instance runs. We also make
+ * sure there is no pending NAPI disable.
*/
static inline int napi_schedule_prep(struct napi_struct *n)
{
- return !test_and_set_bit(NAPI_STATE_SCHED, &n->state);
+ return !napi_disable_pending(n) &&
+ !test_and_set_bit(NAPI_STATE_SCHED, &n->state);
}
/**
@@ -389,8 +397,10 @@ static inline void napi_complete(struct napi_struct *n)
*/
static inline void napi_disable(struct napi_struct *n)
{
+ set_bit(NAPI_STATE_DISABLE, &n->state);
while (test_and_set_bit(NAPI_STATE_SCHED, &n->state))
msleep(1);
+ clear_bit(NAPI_STATE_DISABLE, &n->state);
}
/**
@@ -1268,7 +1278,7 @@ static inline u32 netif_msg_init(int debug_value, int
default_msg_enable_bits)
static inline int netif_rx_schedule_prep(struct net_device *dev,
struct napi_struct *napi)
{
- return netif_running(dev) && napi_schedule_prep(napi);
+ return napi_schedule_prep(napi);
}
/* Add interface to tail of rx poll list. This assumes that _prep has
-
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