On Tue, Mar 14, 2017 at 05:18:52PM +0900, Byungchul Park wrote:
> +struct hist_lock {
> + /*
> + * Each work of workqueue might run in a different context,
> + * thanks to concurrency support of workqueue. So we have to
> + * distinguish each work to avoid false positive.
> + */
> + unsigned int work_id;
> };
> @@ -1749,6 +1749,14 @@ struct task_struct {
> struct held_lock held_locks[MAX_LOCK_DEPTH];
> gfp_t lockdep_reclaim_gfp;
> #endif
> +#ifdef CONFIG_LOCKDEP_CROSSRELEASE
> +#define MAX_XHLOCKS_NR 64UL
> + struct hist_lock *xhlocks; /* Crossrelease history locks */
> + unsigned int xhlock_idx;
> + unsigned int xhlock_idx_soft; /* For backing up at softirq entry */
> + unsigned int xhlock_idx_hard; /* For backing up at hardirq entry */
> + unsigned int work_id;
> +#endif
> #ifdef CONFIG_UBSAN
> unsigned int in_ubsan;
> #endif
> +/*
> + * Crossrelease needs to distinguish each work of workqueues.
> + * Caller is supposed to be a worker.
> + */
> +void crossrelease_work_start(void)
> +{
> + if (current->xhlocks)
> + current->work_id++;
> +}
> +/*
> + * Only access local task's data, so irq disable is only required.
> + */
> +static int same_context_xhlock(struct hist_lock *xhlock)
> +{
> + struct task_struct *curr = current;
> +
> + /* In the case of hardirq context */
> + if (curr->hardirq_context) {
> + if (xhlock->hlock.irq_context & 2) /* 2: bitmask for hardirq */
> + return 1;
> + /* In the case of softriq context */
> + } else if (curr->softirq_context) {
> + if (xhlock->hlock.irq_context & 1) /* 1: bitmask for softirq */
> + return 1;
> + /* In the case of process context */
> + } else {
> + if (xhlock->work_id == curr->work_id)
> + return 1;
> + }
> + return 0;
> +}
I still don't like work_id; it doesn't have anything to do with
workqueues per se, other than the fact that they end up using it.
It's a history generation id; touching it completely invalidates our
history. Workqueues need this because they run independent work from the
same context.
But the same is true for other sites. Last time I suggested
lockdep_assert_empty() to denote all suck places (and note we already
have lockdep_sys_exit() that hooks into the return to user path).
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