[PATCH 04/21] perf_events: Handle persistent events accordingly
in [Kernel]
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From: Borislav Petkov on 1 Jul 2010 12:00 From: Borislav Petkov <borislav.petkov(a)amd.com> Add a persistent events flag which is passed to sys_perf_event_open(). Also, teach the perf syscall to differentiate between previously allocated persistent events and new ones which are about to be created. Signed-off-by: Borislav Petkov <borislav.petkov(a)amd.com> --- include/linux/perf_event.h | 5 +++-- kernel/perf_event.c | 28 +++++++++++++++++++++++++--- 2 files changed, 28 insertions(+), 5 deletions(-) diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index cb242bd..1d7907a 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -452,8 +452,9 @@ enum perf_callchain_context { PERF_CONTEXT_MAX = (__u64)-4095, }; -#define PERF_FLAG_FD_NO_GROUP (1U << 0) -#define PERF_FLAG_FD_OUTPUT (1U << 1) +#define PERF_FLAG_FD_NO_GROUP (1U << 0) +#define PERF_FLAG_FD_OUTPUT (1U << 1) +#define PERF_FLAG_EVENT_PERSISTENT (1U << 2) #ifdef __KERNEL__ /* diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 168764b..8b41a4e 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -5107,7 +5107,9 @@ SYSCALL_DEFINE5(perf_event_open, int err; /* for future expandability... */ - if (flags & ~(PERF_FLAG_FD_NO_GROUP | PERF_FLAG_FD_OUTPUT)) + if (flags & ~(PERF_FLAG_FD_NO_GROUP | + PERF_FLAG_FD_OUTPUT | + PERF_FLAG_EVENT_PERSISTENT)) return -EINVAL; err = perf_copy_attr(attr_uptr, &attr); @@ -5175,8 +5177,23 @@ SYSCALL_DEFINE5(perf_event_open, goto err_put_context; } - event = perf_event_alloc(&attr, cpu, ctx, group_leader, - NULL, NULL, GFP_KERNEL); + if (flags & PERF_FLAG_EVENT_PERSISTENT) { + mutex_lock(&ctx->mutex); + raw_spin_lock(&ctx->lock); + + event = find_event_in_context(&attr, ctx); + + raw_spin_unlock(&ctx->lock); + mutex_unlock(&ctx->mutex); + + if (!event) { + printk(KERN_WARNING "Hmm, uninitialized persistent event?!"); + return -EINVAL; + } + } else + event = perf_event_alloc(&attr, cpu, ctx, group_leader, + NULL, NULL, GFP_KERNEL); + if (IS_ERR(event)) { err = PTR_ERR(event); goto err_put_context; @@ -5195,6 +5212,10 @@ SYSCALL_DEFINE5(perf_event_open, } event->filp = event_file; + + if (flags & PERF_FLAG_EVENT_PERSISTENT) + goto out_drop_ref; + WARN_ON_ONCE(ctx->parent_ctx); mutex_lock(&ctx->mutex); perf_install_in_context(ctx, event, cpu); @@ -5207,6 +5228,7 @@ SYSCALL_DEFINE5(perf_event_open, list_add_tail(&event->owner_entry, ¤t->perf_event_list); mutex_unlock(¤t->perf_event_mutex); +out_drop_ref: /* * Drop the reference on the group_event after placing the * new event on the sibling_list. This ensures destruction -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |