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dm9000: locking bugfix
This fixes a locking bug in the dm9000 driver. It calls request_irq() without setting IRQF_DISABLED ... which is correct for handlers that support IRQ sharing, since that behavior is not guaranteed for shared IRQs. However, its IRQ handler then wrongly assumes that IRQs are blocked. So the fix just uses the right spinlock primitives in the IRQ handler. NOTE: this is a classic example of the type of bug which lockdep currently masks by forcibly setting IRQF_DISABLED on IRQ handlers that did not request that flag. Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: David S. Miller <davem@davemloft.net>
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6580f57d48
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1 changed files with 4 additions and 2 deletions
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@ -930,13 +930,15 @@ static irqreturn_t dm9000_interrupt(int irq, void *dev_id)
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struct net_device *dev = dev_id;
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board_info_t *db = netdev_priv(dev);
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int int_status;
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unsigned long flags;
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u8 reg_save;
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dm9000_dbg(db, 3, "entering %s\n", __func__);
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/* A real interrupt coming */
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spin_lock(&db->lock);
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/* holders of db->lock must always block IRQs */
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spin_lock_irqsave(&db->lock, flags);
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/* Save previous register address */
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reg_save = readb(db->io_addr);
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@ -972,7 +974,7 @@ static irqreturn_t dm9000_interrupt(int irq, void *dev_id)
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/* Restore previous register address */
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writeb(reg_save, db->io_addr);
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spin_unlock(&db->lock);
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spin_unlock_irqrestore(&db->lock, flags);
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return IRQ_HANDLED;
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}
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