Kernel utility functions

upper_32_bits — return bits 32-63 of a number
lower_32_bits — return bits 0-31 of a number
might_sleep — annotation for functions that can sleep
clamp — return a value clamped to a given range with strict typechecking
clamp_t — return a value clamped to a given range using a given type
clamp_val — return a value clamped to a given range using val's type
container_of — cast a member of a structure out to the containing structure
printk — print a kernel message
acquire_console_sem — lock the console system for exclusive use.
release_console_sem — unlock the console system
console_conditional_schedule — yield the CPU if required
printk_timed_ratelimit — caller-controlled printk ratelimiting
panic — halt the system
print_tainted — return a string to represent the kernel taint state.
emergency_restart — reboot the system
kernel_restart — reboot the system
kernel_halt — halt the system
kernel_power_off — power_off the system
set_groups — Change a group subscription in a set of credentials
set_current_groups — Change current's group subscription
orderly_poweroff — Trigger an orderly system poweroff
synchronize_rcu — wait until a grace period has elapsed.
rcu_barrier — Wait until all in-flight call_rcu callbacks complete.
rcu_barrier_bh — Wait until all in-flight call_rcu_bh callbacks complete.
rcu_barrier_sched — Wait for in-flight call_rcu_sched callbacks.