Kernel Locking Matrix

	IRQ Handler A	IRQ Handler B	Softirq A	Softirq B	Tasklet A	Tasklet B	Timer A	Timer B	User Context A	User Context B
IRQ Handler A	None
IRQ Handler B	SLIS	None
Softirq A	SLI	SLI	SL
Softirq B	SLI	SLI	SL	SL
Tasklet A	SLI	SLI	SL	SL	None
Tasklet B	SLI	SLI	SL	SL	SL	None
Timer A	SLI	SLI	SL	SL	SL	SL	None
Timer B	SLI	SLI	SL	SL	SL	SL	SL	None
User Context A	SLI	SLI	SLBH	SLBH	SLBH	SLBH	SLBH	SLBH	None
User Context B	SLI	SLI	SLBH	SLBH	SLBH	SLBH	SLBH	SLBH	MLI	None

Table 5.2. Legend for Locking Requirements Table

SLIS	spin_lock_irqsave
SLI	spin_lock_irq
SL	spin_lock
SLBH	spin_lock_bh
MLI	mutex_lock_interruptible