Messages in this thread | | | Date | Tue, 22 Apr 2014 16:27:59 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 04/16] perf, mmap: Factor out perf_get_fd() |
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On Mon, Apr 07, 2014 at 05:04:26PM +0200, Jean Pihet wrote: > From: Robert Richter <robert.richter@linaro.org> > > This new function creates a new fd for an event. We need this later to > get a fd from a persistent event. > > Signed-off-by: Robert Richter <robert.richter@linaro.org> > Signed-off-by: Robert Richter <rric@kernel.org> > Signed-off-by: Jean Pihet <jean.pihet@linaro.org> > --- > kernel/events/core.c | 14 ++++++++------ > kernel/events/internal.h | 1 + > 2 files changed, 9 insertions(+), 6 deletions(-) > > diff --git a/kernel/events/core.c b/kernel/events/core.c > index 22ec8f0..9857475 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -4206,6 +4206,11 @@ static const struct file_operations perf_fops = { > .fasync = perf_fasync, > }; > > +int perf_get_fd(struct perf_event *event, int f_flags) > +{ > + return anon_inode_getfd("[perf_event]", &perf_fops, event, f_flags); > +} > + > /* > * Perf event wakeup > * > @@ -7028,7 +7033,6 @@ SYSCALL_DEFINE5(perf_event_open, > struct perf_event *event, *sibling; > struct perf_event_attr attr; > struct perf_event_context *ctx; > - struct file *event_file = NULL; > struct fd group = {NULL, 0}; > struct task_struct *task = NULL; > struct pmu *pmu; > @@ -7189,10 +7193,9 @@ SYSCALL_DEFINE5(perf_event_open, > goto err_context; > } > > - event_file = anon_inode_getfile("[perf_event]", &perf_fops, event, > - f_flags); > - if (IS_ERR(event_file)) { > - err = PTR_ERR(event_file); > + event_fd = perf_get_fd(event, f_flags); > + if (event_fd < 0) { > + err = event_fd; > goto err_context; > } > > @@ -7257,7 +7260,6 @@ SYSCALL_DEFINE5(perf_event_open, > * perf_group_detach(). > */ > fdput(group); > - fd_install(event_fd, event_file); > return event_fd; > > err_context:
ISTR there being a good reason we only install the FD at the very last moment. Of course I cannot quite recall it :/
I suspect it had something to do with not being able to fudge the state while its being set-up or somesuch.
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