Data races are often hard to detect in device drivers. According to our study of Linux driver patches that fix data races, about 39% of patches involve a pattern that we callinconsistent locking discipline. Specifically, if a variable is accessed within two concurrently executed functions, the sets of locks held around each access are disjoint, at least one of the locksets is non-empty, and at least one of the involved accesses is a write, then a data race may occur. In this paper, we present a hybrid static-dynamic analysis approach, named SDILP, to detect data races caused by inconsistent locking discipline in device drivers. SDILP has a dynamic lockset analysis to detect data races at runtime, and a static lockset analysis to detect more data races based on the dynamic-analysis results. It also performs a static taint analysis to reduce the number of variable accesses monitored by the dynamic analysis. Compared to our previous dynamic approach DILP (Chen et al., 2019), introducing static analysis allows SDILP to achieve better performance and find more data races. We evaluate SDILP on 12 drivers in Linux 5.4, and find 117 real data races, 50 of which have been confirmed by driver developers.

Data races are often hard to detect in device drivers, due to the non-determinism of concurrent execution. According to our study of Linux driver patches that fix data races, more than 38% of patches involve a pattern that we call inconsistent lock protection. Specifically, if a variable is accessed within two concurrently executed functions, the sets of locks held around each access are disjoint, at least one of the locksets is non-empty, and at least one of the involved accesses is a write, then a data race may occur.In this paper, we present a runtime analysis approach, named DILP, to detect data races caused by inconsistent lock protection in device drivers. By monitoring driver execution, DILP collects the information about runtime variable accesses and executed functions. Then after driver execution, DILP analyzes the collected information to detect and report data races caused by inconsistent lock protection. We evaluate DILP on 12 device drivers in Linux 4.16.9, and find 25 real data races.