LockLint Overview

When analyzing locks and how they are used, LockLint detects a common cause of data races: failure to hold the appropriate lock while accessing a variable.

Table 5-1, Table 5-2, and Table 5-3 list the routines of the Solaris and POSIX libthread APIs recognized by LockLint.

Table 5-1 Reader -Writer Locks

Solaris	Kernel (Solaris only)
rw_rdlock, rw_wrlock rw_unlock rw_tryrdlock, rw_trywrlock	rw_enter rw_exit rw_tryenter rw_downgrade rw_tryupgrade

Table 5-2 Condition Variables

Solaris	POSIX	Kernel (Solaris only)
cond_broadcast cond_wait     cond_timedwait cond_signal	pthread_cond_broadcast pthread_cond_wait     pthread_cond_timedwait   pthread_cond_signal	cv_broadcast cv_wait cv_wait_sig cv_wait_sig_swap cv_timedwait cv_timedwait_sig cv_signal

Table 5-3 Mutex (Mutual Exclusion) Locks

Solaris	POSIX	Kernel (Solaris only)
mutex_lock mutex_unlock mutex_trylock	pthread_mutex_lock pthread_mutex_unlock pthread_mutex_trylock	mutex_enter mutex_exit mutex_tryenter

Additionally, LockLint recognizes the structure types shown in Table 5-4.

Table 5-4 Lock Structures

Solaris	POSIX	Kernel (Solaris only)
mutex_t	pthread_mutex_t	kmutex_t
rwlock_t		krwlock_t

LockLint reports several kinds of basic information about the modules it analyzes, including:

• Locking side effects of functions. Unknown side effects can lead to data races or deadlocks.

• Accesses to variables that are not consistently protected by at least one lock, and accesses that violate assertions about which locks protect them. This information can point to a potential data race.

• Cycles and inconsistent lock-order acquisitions. This information can point to potential deadlocks.

• Variables that were protected by a given lock. This can assist in judging the appropriateness of the chosen granularity, that is, which variables are protected by which locks.

LockLint provides subcommands for specifying assertions about the application. During the analysis phase, LockLint reports any violation of the assertions.

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Note -

Add assertions liberally, and use the analysis phase to refine assertions and to make sure that new code does not violate the established locking conventions of the program.

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