Re: [PATCH 2/3] remove irq_sem from e1000

[Chris Snook]

Kok, Auke wrote:
Chris Snook wrote:
From: Chris Snook <[EMAIL PROTECTED]>
Remove unnecessary irq_sem accounting from e1000.  Tested with no 
problems.


the major problem with this is that one of the e1000 parts (82547) still 
requires the irq_sem. I doubt that you tested that card specifically. 
I'm still not convinced that this patch is therefore a good idea. the 
patch for ixgb is another thing, but for e1000 we definately want to 
keep the irq_sem around until we get some definitive testing on all 
adapters.

So, this patch will stay under suspicion a bit longer. Same for the ixgb 
version.

Auke

Requires?  I acknowledge that the code is used in a special codepath for 
those cards, but it appears to be used in the same unnecessary way it is 
used everywhere else.

My testing was limited to an onboard NIC on a fairly old box I don't 
have access to anymore, as well as the e1000-derived atl1 driver.  My 
primary justification is code inspection.  The code just doesn't do 
anything productive.

        -- Chris


Signed-off-by: Chris Snook <[EMAIL PROTECTED]>
--
diff -urp linux-2.6.20-git14.orig/drivers/net/e1000/e1000.h
linux-2.6.20-git14/drivers/net/e1000/e1000.h
--- linux-2.6.20-git14.orig/drivers/net/e1000/e1000.h    2007-02-19
14:32:15.000000000 -0500
+++ linux-2.6.20-git14/drivers/net/e1000/e1000.h    2007-02-19 
15:07:37.000000000
-0500
@@ -252,7 +252,6 @@ struct e1000_adapter {
 #ifdef CONFIG_E1000_NAPI
     spinlock_t tx_queue_lock;
 #endif
-    atomic_t irq_sem;
     unsigned int total_tx_bytes;
     unsigned int total_tx_packets;
     unsigned int total_rx_bytes;
diff -urp linux-2.6.20-git14.orig/drivers/net/e1000/e1000_main.c
linux-2.6.20-git14/drivers/net/e1000/e1000_main.c
--- linux-2.6.20-git14.orig/drivers/net/e1000/e1000_main.c    2007-02-19
14:32:15.000000000 -0500
+++ linux-2.6.20-git14/drivers/net/e1000/e1000_main.c    2007-02-19
15:09:28.000000000 -0500
@@ -349,7 +349,6 @@ static void e1000_free_irq(struct e1000_
 static void
 e1000_irq_disable(struct e1000_adapter *adapter)
 {
-    atomic_inc(&adapter->irq_sem);
     E1000_WRITE_REG(&adapter->hw, IMC, ~0);
     E1000_WRITE_FLUSH(&adapter->hw);
     synchronize_irq(adapter->pdev->irq);
@@ -363,10 +362,8 @@ e1000_irq_disable(struct e1000_adapter *
 static void
 e1000_irq_enable(struct e1000_adapter *adapter)
 {
-    if (likely(atomic_dec_and_test(&adapter->irq_sem))) {
-        E1000_WRITE_REG(&adapter->hw, IMS, IMS_ENABLE_MASK);
-        E1000_WRITE_FLUSH(&adapter->hw);
-    }
+    E1000_WRITE_REG(&adapter->hw, IMS, IMS_ENABLE_MASK);
+    E1000_WRITE_FLUSH(&adapter->hw);
 }

 static void
@@ -1336,7 +1333,6 @@ e1000_sw_init(struct e1000_adapter *adap
     spin_lock_init(&adapter->tx_queue_lock);
 #endif

-    atomic_set(&adapter->irq_sem, 1);
     spin_lock_init(&adapter->stats_lock);

     set_bit(__E1000_DOWN, &adapter->flags);
@@ -3758,11 +3754,6 @@ e1000_intr_msi(int irq, void *data)
 #endif
     uint32_t icr = E1000_READ_REG(hw, ICR);

-#ifdef CONFIG_E1000_NAPI
-    /* read ICR disables interrupts using IAM, so keep up with our
-     * enable/disable accounting */
-    atomic_inc(&adapter->irq_sem);
-#endif
     if (icr & (E1000_ICR_RXSEQ | E1000_ICR_LSC)) {
         hw->get_link_status = 1;
         /* 80003ES2LAN workaround-- For packet buffer work-around on
@@ -3832,13 +3823,6 @@ e1000_intr(int irq, void *data)
     if (unlikely(hw->mac_type >= e1000_82571 &&
                  !(icr & E1000_ICR_INT_ASSERTED)))
         return IRQ_NONE;
-
-    /* Interrupt Auto-Mask...upon reading ICR,
-     * interrupts are masked.  No need for the
-     * IMC write, but it does mean we should
-     * account for it ASAP. */
-    if (likely(hw->mac_type >= e1000_82571))
-        atomic_inc(&adapter->irq_sem);
 #endif

     if (unlikely(icr & (E1000_ICR_RXSEQ | E1000_ICR_LSC))) {
@@ -3862,7 +3846,6 @@ e1000_intr(int irq, void *data)
 #ifdef CONFIG_E1000_NAPI
     if (unlikely(hw->mac_type < e1000_82571)) {
         /* disable interrupts, without the synchronize_irq bit */
-        atomic_inc(&adapter->irq_sem);
         E1000_WRITE_REG(hw, IMC, ~0);
         E1000_WRITE_FLUSH(hw);
     }
@@ -3888,7 +3871,6 @@ e1000_intr(int irq, void *data)
      * de-assertion state.
      */
     if (hw->mac_type == e1000_82547 || hw->mac_type == 
e1000_82547_rev_2) {
-        atomic_inc(&adapter->irq_sem);
         E1000_WRITE_REG(hw, IMC, ~0);
     }

-
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

-
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at  http://vger.kernel.org/majordomo-info.html