Re: [PATCH 2.6.25-rc6] Fix itimer/many thread hang.

Ingo Molnar
2008-03-28T10:29:17Z

* Frank Mayhar <fmayhar@google.com> wrote:

> +static inline void thread_group_times_init(struct signal_struct *sig)
> +{
> + sig->thread_group_times = NULL;
> +}
> +
> +static inline void thread_group_times_free(struct signal_struct *sig)
> +{
> + if (sig->thread_group_times)
> + free_percpu(sig->thread_group_times);
> +}
> +
> +/*
> + * Allocate the thread_group_cputime struct appropriately and fill in the current
> + * values of the fields. Called from do_setitimer() when setting an interval
> + * timer (ITIMER_PROF or ITIMER_VIRTUAL). Assumes interrupts are enabled when
> + * it's called. Note that there is no corresponding deallocation done from
> + * do_setitimer(); the structure is freed at process exit.
> + */
> +static inline int thread_group_times_alloc(struct task_struct *tsk)
> +{
> + struct signal_struct *sig = tsk->signal;
> + struct thread_group_cputime *thread_group_times;
> + struct task_struct *t;
> + cputime_t utime, stime;
> + unsigned long long sum_exec_runtime;
> +
> + /*
> + * If we don't already have a thread_group_cputime struct, allocate
> + * one and fill it in with the accumulated times.
> + */
> + if (sig->thread_group_times)
> + return 0;
> + thread_group_times = alloc_percpu(struct thread_group_cputime);
> + if (thread_group_times == NULL)
> + return -ENOMEM;
> + read_lock(&tasklist_lock);
> + spin_lock_irq(&tsk->sighand->siglock);
> + if (sig->thread_group_times) {
> + spin_unlock_irq(&tsk->sighand->siglock);
> + read_unlock(&tasklist_lock);
> + free_percpu(thread_group_times);
> + return 0;
> + }
> + sig->thread_group_times = thread_group_times;
> + utime = sig->utime;
> + stime = sig->stime;
> + sum_exec_runtime = tsk->se.sum_exec_runtime;
> + t = tsk;
> + do {
> + utime = cputime_add(utime, t->utime);
> + stime = cputime_add(stime, t->stime);
> + sum_exec_runtime += t->se.sum_exec_runtime;
> + } while_each_thread(tsk, t);
> + thread_group_times = per_cpu_ptr(sig->thread_group_times, get_cpu());
> + thread_group_times->utime = utime;
> + thread_group_times->stime = stime;
> + thread_group_times->sum_exec_runtime = sum_exec_runtime;
> + put_cpu_no_resched();
> + spin_unlock_irq(&tsk->sighand->siglock);
> + read_unlock(&tasklist_lock);
> + return 0;
> +}

please dont put such a huge inline into a header.

> +
> +#define thread_group_update(sig, field, val, op) ({ \
> + if (sig && sig->thread_group_times) { \
> + int cpu; \
> + struct thread_group_cputime *thread_group_times; \
> + \
> + cpu = get_cpu(); \
> + thread_group_times = \
> + per_cpu_ptr(sig->thread_group_times, cpu); \
> + thread_group_times->field = \
> + op(thread_group_times->field, val); \
> + put_cpu_no_resched(); \
> + } \
> +})

nor use any macros that includes code.

> +static inline int thread_group_cputime(struct thread_group_cputime *thread_group_times,
> + struct signal_struct *sig)

ditto, line length as well.

> + if (!sig->thread_group_times)
> + return(0);

return 0 is the proper form - please run your patch through
scripts/checkpatch.pl.

Ingo