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__TEST_AND_SET_BIT(9) Basic C Library Functions __TEST_AND_SET_BIT(9)

NAME

__test_and_set_bit - Set a bit and return its old value

SYNOPSIS

bool __test_and_set_bit(long nr, volatile unsigned long * addr);

ARGUMENTS

long nr

Bit to set

volatile unsigned long * addr

Address to count from

DESCRIPTION

This operation is non-atomic and can be reordered. If two examples of this operation race, one can appear to succeed but actually fail. You must protect multiple accesses with a lock.

COPYRIGHT

June 2017 Kernel Hackers Manual 4.11