[5/5] io_uring: add IORING_OP_WAITID support
Commit Message
This adds support for an async version of waitid(2), in a fully async
version. If an event isn't immediately available, wait for a callback
to trigger a retry.
The format of the sqe is as follows:
sqe->len The 'which', the idtype being queried/waited for.
sqe->fd The 'pid' (or id) being waited for.
sqe->file_index The 'options' being set.
sqe->addr2 A pointer to siginfo_t, if any, being filled in.
buf_index, add3, and waitid_flags are reserved/unused for now.
waitid_flags will be used for options for this request type. One
interesting use case may be to add multi-shot support, so that the
request stays armed and posts a notification every time a monitored
process state change occurs.
Note that this does not support rusage, on Arnd's recommendation.
See the waitid(2) man page for details on the arguments.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
include/linux/io_uring_types.h | 2 +
include/uapi/linux/io_uring.h | 2 +
io_uring/Makefile | 2 +-
io_uring/cancel.c | 5 +
io_uring/io_uring.c | 3 +
io_uring/opdef.c | 9 ++
io_uring/waitid.c | 271 +++++++++++++++++++++++++++++++++
io_uring/waitid.h | 15 ++
8 files changed, 308 insertions(+), 1 deletion(-)
create mode 100644 io_uring/waitid.c
create mode 100644 io_uring/waitid.h
Comments
On Tue, Jul 11, 2023, at 22:43, Jens Axboe wrote:
> This adds support for an async version of waitid(2), in a fully async
> version. If an event isn't immediately available, wait for a callback
> to trigger a retry.
>
> The format of the sqe is as follows:
>
> sqe->len The 'which', the idtype being queried/waited for.
> sqe->fd The 'pid' (or id) being waited for.
> sqe->file_index The 'options' being set.
> sqe->addr2 A pointer to siginfo_t, if any, being filled in.
>
> buf_index, add3, and waitid_flags are reserved/unused for now.
> waitid_flags will be used for options for this request type. One
> interesting use case may be to add multi-shot support, so that the
> request stays armed and posts a notification every time a monitored
> process state change occurs.
>
> Note that this does not support rusage, on Arnd's recommendation.
>
> See the waitid(2) man page for details on the arguments.
>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Does this require argument conversion for compat tasks?
Even without the rusage argument, I think the siginfo
remains incompatible with 32-bit tasks, unfortunately.
Arnd
On 7/11/23 3:11?PM, Arnd Bergmann wrote:
> On Tue, Jul 11, 2023, at 22:43, Jens Axboe wrote:
>> This adds support for an async version of waitid(2), in a fully async
>> version. If an event isn't immediately available, wait for a callback
>> to trigger a retry.
>>
>> The format of the sqe is as follows:
>>
>> sqe->len The 'which', the idtype being queried/waited for.
>> sqe->fd The 'pid' (or id) being waited for.
>> sqe->file_index The 'options' being set.
>> sqe->addr2 A pointer to siginfo_t, if any, being filled in.
>>
>> buf_index, add3, and waitid_flags are reserved/unused for now.
>> waitid_flags will be used for options for this request type. One
>> interesting use case may be to add multi-shot support, so that the
>> request stays armed and posts a notification every time a monitored
>> process state change occurs.
>>
>> Note that this does not support rusage, on Arnd's recommendation.
>>
>> See the waitid(2) man page for details on the arguments.
>>
>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>
> Does this require argument conversion for compat tasks?
>
> Even without the rusage argument, I think the siginfo
> remains incompatible with 32-bit tasks, unfortunately.
Hmm yes good point, if compat_siginfo and siginfo are different, then it
does need handling for that. Would be a trivial addition, I'll make that
change. Thanks Arnd!
On 7/11/23 3:22 PM, Jens Axboe wrote:
> On 7/11/23 3:11?PM, Arnd Bergmann wrote:
>> On Tue, Jul 11, 2023, at 22:43, Jens Axboe wrote:
>>> This adds support for an async version of waitid(2), in a fully async
>>> version. If an event isn't immediately available, wait for a callback
>>> to trigger a retry.
>>>
>>> The format of the sqe is as follows:
>>>
>>> sqe->len The 'which', the idtype being queried/waited for.
>>> sqe->fd The 'pid' (or id) being waited for.
>>> sqe->file_index The 'options' being set.
>>> sqe->addr2 A pointer to siginfo_t, if any, being filled in.
>>>
>>> buf_index, add3, and waitid_flags are reserved/unused for now.
>>> waitid_flags will be used for options for this request type. One
>>> interesting use case may be to add multi-shot support, so that the
>>> request stays armed and posts a notification every time a monitored
>>> process state change occurs.
>>>
>>> Note that this does not support rusage, on Arnd's recommendation.
>>>
>>> See the waitid(2) man page for details on the arguments.
>>>
>>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>>
>> Does this require argument conversion for compat tasks?
>>
>> Even without the rusage argument, I think the siginfo
>> remains incompatible with 32-bit tasks, unfortunately.
>
> Hmm yes good point, if compat_siginfo and siginfo are different, then it
> does need handling for that. Would be a trivial addition, I'll make that
> change. Thanks Arnd!
Should be fixed in the current version:
https://git.kernel.dk/cgit/linux/commit/?h=io_uring-waitid&id=08f3dc9b7cedbd20c0f215f25c9a7814c6c601cc
On Tue, Jul 11, 2023 at 04:18:13PM -0600, Jens Axboe wrote:
> On 7/11/23 3:22 PM, Jens Axboe wrote:
> > On 7/11/23 3:11?PM, Arnd Bergmann wrote:
> >> On Tue, Jul 11, 2023, at 22:43, Jens Axboe wrote:
> >>> This adds support for an async version of waitid(2), in a fully async
> >>> version. If an event isn't immediately available, wait for a callback
> >>> to trigger a retry.
> >>>
> >>> The format of the sqe is as follows:
> >>>
> >>> sqe->len The 'which', the idtype being queried/waited for.
> >>> sqe->fd The 'pid' (or id) being waited for.
> >>> sqe->file_index The 'options' being set.
> >>> sqe->addr2 A pointer to siginfo_t, if any, being filled in.
> >>>
> >>> buf_index, add3, and waitid_flags are reserved/unused for now.
> >>> waitid_flags will be used for options for this request type. One
> >>> interesting use case may be to add multi-shot support, so that the
> >>> request stays armed and posts a notification every time a monitored
> >>> process state change occurs.
> >>>
> >>> Note that this does not support rusage, on Arnd's recommendation.
> >>>
> >>> See the waitid(2) man page for details on the arguments.
> >>>
> >>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> >>
> >> Does this require argument conversion for compat tasks?
> >>
> >> Even without the rusage argument, I think the siginfo
> >> remains incompatible with 32-bit tasks, unfortunately.
> >
> > Hmm yes good point, if compat_siginfo and siginfo are different, then it
> > does need handling for that. Would be a trivial addition, I'll make that
> > change. Thanks Arnd!
>
> Should be fixed in the current version:
>
> https://git.kernel.dk/cgit/linux/commit/?h=io_uring-waitid&id=08f3dc9b7cedbd20c0f215f25c9a7814c6c601cc
In kernel/signal.c in pidfd_send_signal() we have
copy_siginfo_from_user_any() it seems that a similar version
copy_siginfo_to_user_any() might be something to consider. We do have
copy_siginfo_to_user32() and copy_siginfo_to_user(). But I may lack
context why this wouldn't work here.
On Fri, Jul 14, 2023, at 17:47, Christian Brauner wrote:
> On Tue, Jul 11, 2023 at 04:18:13PM -0600, Jens Axboe wrote:
>> On 7/11/23 3:22 PM, Jens Axboe wrote:
>> > On 7/11/23 3:11?PM, Arnd Bergmann wrote:
>> >> Does this require argument conversion for compat tasks?
>> >>
>> >> Even without the rusage argument, I think the siginfo
>> >> remains incompatible with 32-bit tasks, unfortunately.
>> >
>> > Hmm yes good point, if compat_siginfo and siginfo are different, then it
>> > does need handling for that. Would be a trivial addition, I'll make that
>> > change. Thanks Arnd!
>>
>> Should be fixed in the current version:
>>
>> https://git.kernel.dk/cgit/linux/commit/?h=io_uring-waitid&id=08f3dc9b7cedbd20c0f215f25c9a7814c6c601cc
>
> In kernel/signal.c in pidfd_send_signal() we have
> copy_siginfo_from_user_any() it seems that a similar version
> copy_siginfo_to_user_any() might be something to consider. We do have
> copy_siginfo_to_user32() and copy_siginfo_to_user(). But I may lack
> context why this wouldn't work here.
We could add a copy_siginfo_to_user_any(), but I think open-coding
it is easier here, since the in_compat_syscall() check does not
work inside of the io_uring kernel thread, it has to be
"if (req->ctx->compat)" in order to match the wordsize of the task
that started the request.
Using copy_siginfo_to_user32() and copy_siginfo_to_user() is
probably a good idea though, it's often faster and less
error-prone than writing each member separately.
Arnd
On 7/14/23 12:33?PM, Arnd Bergmann wrote:
> On Fri, Jul 14, 2023, at 17:47, Christian Brauner wrote:
>> On Tue, Jul 11, 2023 at 04:18:13PM -0600, Jens Axboe wrote:
>>> On 7/11/23 3:22?PM, Jens Axboe wrote:
>>>> On 7/11/23 3:11?PM, Arnd Bergmann wrote:
>
>>>>> Does this require argument conversion for compat tasks?
>>>>>
>>>>> Even without the rusage argument, I think the siginfo
>>>>> remains incompatible with 32-bit tasks, unfortunately.
>>>>
>>>> Hmm yes good point, if compat_siginfo and siginfo are different, then it
>>>> does need handling for that. Would be a trivial addition, I'll make that
>>>> change. Thanks Arnd!
>>>
>>> Should be fixed in the current version:
>>>
>>> https://git.kernel.dk/cgit/linux/commit/?h=io_uring-waitid&id=08f3dc9b7cedbd20c0f215f25c9a7814c6c601cc
>>
>> In kernel/signal.c in pidfd_send_signal() we have
>> copy_siginfo_from_user_any() it seems that a similar version
>> copy_siginfo_to_user_any() might be something to consider. We do have
>> copy_siginfo_to_user32() and copy_siginfo_to_user(). But I may lack
>> context why this wouldn't work here.
>
> We could add a copy_siginfo_to_user_any(), but I think open-coding
> it is easier here, since the in_compat_syscall() check does not
> work inside of the io_uring kernel thread, it has to be
> "if (req->ctx->compat)" in order to match the wordsize of the task
> that started the request.
Yeah, unifying this stuff did cross my mind when adding another one.
Which I think could still be done, you'd just need to pass in a 'compat'
parameter similar to how it's done for iovec importing.
But if it's ok with everybody I'd rather do that as a cleanup post this.
> Using copy_siginfo_to_user32() and copy_siginfo_to_user() is
> probably a good idea though, it's often faster and less
> error-prone than writing each member separately.
I was just pattern matching on the other use cases. I'll take a look at
the siginfo copy helpers, thanks!
On Fri, Jul 14, 2023, at 22:14, Jens Axboe wrote:
> On 7/14/23 12:33?PM, Arnd Bergmann wrote:
>> On Fri, Jul 14, 2023, at 17:47, Christian Brauner wrote:
>>> On Tue, Jul 11, 2023 at 04:18:13PM -0600, Jens Axboe wrote:
>>>>>> Does this require argument conversion for compat tasks?
>>>>>>
>>>>>> Even without the rusage argument, I think the siginfo
>>>>>> remains incompatible with 32-bit tasks, unfortunately.
>>>>>
>>>>> Hmm yes good point, if compat_siginfo and siginfo are different, then it
>>>>> does need handling for that. Would be a trivial addition, I'll make that
>>>>> change. Thanks Arnd!
>>>>
>>>> Should be fixed in the current version:
>>>>
>>>> https://git.kernel.dk/cgit/linux/commit/?h=io_uring-waitid&id=08f3dc9b7cedbd20c0f215f25c9a7814c6c601cc
>>>
>>> In kernel/signal.c in pidfd_send_signal() we have
>>> copy_siginfo_from_user_any() it seems that a similar version
>>> copy_siginfo_to_user_any() might be something to consider. We do have
>>> copy_siginfo_to_user32() and copy_siginfo_to_user(). But I may lack
>>> context why this wouldn't work here.
>>
>> We could add a copy_siginfo_to_user_any(), but I think open-coding
>> it is easier here, since the in_compat_syscall() check does not
>> work inside of the io_uring kernel thread, it has to be
>> "if (req->ctx->compat)" in order to match the wordsize of the task
>> that started the request.
>
> Yeah, unifying this stuff did cross my mind when adding another one.
> Which I think could still be done, you'd just need to pass in a 'compat'
> parameter similar to how it's done for iovec importing.
>
> But if it's ok with everybody I'd rather do that as a cleanup post this.
Sure, keeping that separate seem best.
Looking at what copy_siginfo_from_user_any() actually does, I don't
even think it's worth adapting copy_siginfo_to_user_any() for io_uring,
since it's already just a trivial wrapper, and adding another
argument would add more complexity overall than it saves.
Arnd
On 7/15/23 1:12 AM, Arnd Bergmann wrote:
> On Fri, Jul 14, 2023, at 22:14, Jens Axboe wrote:
>> On 7/14/23 12:33?PM, Arnd Bergmann wrote:
>>> On Fri, Jul 14, 2023, at 17:47, Christian Brauner wrote:
>>>> On Tue, Jul 11, 2023 at 04:18:13PM -0600, Jens Axboe wrote:
>>>>>>> Does this require argument conversion for compat tasks?
>>>>>>>
>>>>>>> Even without the rusage argument, I think the siginfo
>>>>>>> remains incompatible with 32-bit tasks, unfortunately.
>>>>>>
>>>>>> Hmm yes good point, if compat_siginfo and siginfo are different, then it
>>>>>> does need handling for that. Would be a trivial addition, I'll make that
>>>>>> change. Thanks Arnd!
>>>>>
>>>>> Should be fixed in the current version:
>>>>>
>>>>> https://git.kernel.dk/cgit/linux/commit/?h=io_uring-waitid&id=08f3dc9b7cedbd20c0f215f25c9a7814c6c601cc
>>>>
>>>> In kernel/signal.c in pidfd_send_signal() we have
>>>> copy_siginfo_from_user_any() it seems that a similar version
>>>> copy_siginfo_to_user_any() might be something to consider. We do have
>>>> copy_siginfo_to_user32() and copy_siginfo_to_user(). But I may lack
>>>> context why this wouldn't work here.
>>>
>>> We could add a copy_siginfo_to_user_any(), but I think open-coding
>>> it is easier here, since the in_compat_syscall() check does not
>>> work inside of the io_uring kernel thread, it has to be
>>> "if (req->ctx->compat)" in order to match the wordsize of the task
>>> that started the request.
>>
>> Yeah, unifying this stuff did cross my mind when adding another one.
>> Which I think could still be done, you'd just need to pass in a 'compat'
>> parameter similar to how it's done for iovec importing.
>>
>> But if it's ok with everybody I'd rather do that as a cleanup post this.
>
> Sure, keeping that separate seem best.
>
> Looking at what copy_siginfo_from_user_any() actually does, I don't
> even think it's worth adapting copy_siginfo_to_user_any() for io_uring,
> since it's already just a trivial wrapper, and adding another
> argument would add more complexity overall than it saves.
Yeah, took a look too this morning, and not sure there's much to reduce
here that would make it cleaner. I'm going to send out a v2 with this
unchanged, holler if people disagree.
On 7/15/23 8:06?AM, Jens Axboe wrote:
> On 7/15/23 1:12?AM, Arnd Bergmann wrote:
>> On Fri, Jul 14, 2023, at 22:14, Jens Axboe wrote:
>>> On 7/14/23 12:33?PM, Arnd Bergmann wrote:
>>>> On Fri, Jul 14, 2023, at 17:47, Christian Brauner wrote:
>>>>> On Tue, Jul 11, 2023 at 04:18:13PM -0600, Jens Axboe wrote:
>>>>>>>> Does this require argument conversion for compat tasks?
>>>>>>>>
>>>>>>>> Even without the rusage argument, I think the siginfo
>>>>>>>> remains incompatible with 32-bit tasks, unfortunately.
>>>>>>>
>>>>>>> Hmm yes good point, if compat_siginfo and siginfo are different, then it
>>>>>>> does need handling for that. Would be a trivial addition, I'll make that
>>>>>>> change. Thanks Arnd!
>>>>>>
>>>>>> Should be fixed in the current version:
>>>>>>
>>>>>> https://git.kernel.dk/cgit/linux/commit/?h=io_uring-waitid&id=08f3dc9b7cedbd20c0f215f25c9a7814c6c601cc
>>>>>
>>>>> In kernel/signal.c in pidfd_send_signal() we have
>>>>> copy_siginfo_from_user_any() it seems that a similar version
>>>>> copy_siginfo_to_user_any() might be something to consider. We do have
>>>>> copy_siginfo_to_user32() and copy_siginfo_to_user(). But I may lack
>>>>> context why this wouldn't work here.
>>>>
>>>> We could add a copy_siginfo_to_user_any(), but I think open-coding
>>>> it is easier here, since the in_compat_syscall() check does not
>>>> work inside of the io_uring kernel thread, it has to be
>>>> "if (req->ctx->compat)" in order to match the wordsize of the task
>>>> that started the request.
>>>
>>> Yeah, unifying this stuff did cross my mind when adding another one.
>>> Which I think could still be done, you'd just need to pass in a 'compat'
>>> parameter similar to how it's done for iovec importing.
>>>
>>> But if it's ok with everybody I'd rather do that as a cleanup post this.
>>
>> Sure, keeping that separate seem best.
>>
>> Looking at what copy_siginfo_from_user_any() actually does, I don't
>> even think it's worth adapting copy_siginfo_to_user_any() for io_uring,
>> since it's already just a trivial wrapper, and adding another
>> argument would add more complexity overall than it saves.
>
> Yeah, took a look too this morning, and not sure there's much to reduce
> here that would make it cleaner. I'm going to send out a v2 with this
> unchanged, holler if people disagree.
Looking over changes, none have been made so far. So I guess a v2 can
wait a bit. The branch was rebased to add Christian's acked-bys for some
of the patches, and since a branch it was based on (io_uring-futex) got
rebased to accommodate PeterZ's changes.
On 7/15/23 8:06?AM, Jens Axboe wrote:
> On 7/15/23 1:12?AM, Arnd Bergmann wrote:
>> On Fri, Jul 14, 2023, at 22:14, Jens Axboe wrote:
>>> On 7/14/23 12:33?PM, Arnd Bergmann wrote:
>>>> On Fri, Jul 14, 2023, at 17:47, Christian Brauner wrote:
>>>>> On Tue, Jul 11, 2023 at 04:18:13PM -0600, Jens Axboe wrote:
>>>>>>>> Does this require argument conversion for compat tasks?
>>>>>>>>
>>>>>>>> Even without the rusage argument, I think the siginfo
>>>>>>>> remains incompatible with 32-bit tasks, unfortunately.
>>>>>>>
>>>>>>> Hmm yes good point, if compat_siginfo and siginfo are different, then it
>>>>>>> does need handling for that. Would be a trivial addition, I'll make that
>>>>>>> change. Thanks Arnd!
>>>>>>
>>>>>> Should be fixed in the current version:
>>>>>>
>>>>>> https://git.kernel.dk/cgit/linux/commit/?h=io_uring-waitid&id=08f3dc9b7cedbd20c0f215f25c9a7814c6c601cc
>>>>>
>>>>> In kernel/signal.c in pidfd_send_signal() we have
>>>>> copy_siginfo_from_user_any() it seems that a similar version
>>>>> copy_siginfo_to_user_any() might be something to consider. We do have
>>>>> copy_siginfo_to_user32() and copy_siginfo_to_user(). But I may lack
>>>>> context why this wouldn't work here.
>>>>
>>>> We could add a copy_siginfo_to_user_any(), but I think open-coding
>>>> it is easier here, since the in_compat_syscall() check does not
>>>> work inside of the io_uring kernel thread, it has to be
>>>> "if (req->ctx->compat)" in order to match the wordsize of the task
>>>> that started the request.
>>>
>>> Yeah, unifying this stuff did cross my mind when adding another one.
>>> Which I think could still be done, you'd just need to pass in a 'compat'
>>> parameter similar to how it's done for iovec importing.
>>>
>>> But if it's ok with everybody I'd rather do that as a cleanup post this.
>>
>> Sure, keeping that separate seem best.
>>
>> Looking at what copy_siginfo_from_user_any() actually does, I don't
>> even think it's worth adapting copy_siginfo_to_user_any() for io_uring,
>> since it's already just a trivial wrapper, and adding another
>> argument would add more complexity overall than it saves.
>
> Yeah, took a look too this morning, and not sure there's much to reduce
> here that would make it cleaner. I'm going to send out a v2 with this
> unchanged, holler if people disagree.
One thing we could do is the below, but honestly not sure it's worth the
hassle?
diff --git a/io_uring/waitid.c b/io_uring/waitid.c
index 14ffa07e161a..6de1041c4784 100644
--- a/io_uring/waitid.c
+++ b/io_uring/waitid.c
@@ -43,6 +43,8 @@ static bool io_waitid_compat_copy_si(struct io_waitid *iw, int signo)
bool ret;
infop = (struct compat_siginfo __user *) iw->infop;
+ if (!infop)
+ return true;
if (!user_write_access_begin(infop, sizeof(*infop)))
return false;
@@ -66,32 +68,13 @@ static bool io_waitid_compat_copy_si(struct io_waitid *iw, int signo)
static bool io_waitid_copy_si(struct io_kiocb *req, int signo)
{
struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);
- bool ret;
-
- if (!iw->infop)
- return true;
#ifdef CONFIG_COMPAT
if (req->ctx->compat)
return io_waitid_compat_copy_si(iw, signo);
#endif
- if (!user_write_access_begin(iw->infop, sizeof(*iw->infop)))
- return false;
-
- unsafe_put_user(signo, &iw->infop->si_signo, Efault);
- unsafe_put_user(0, &iw->infop->si_errno, Efault);
- unsafe_put_user(iw->info.cause, &iw->infop->si_code, Efault);
- unsafe_put_user(iw->info.pid, &iw->infop->si_pid, Efault);
- unsafe_put_user(iw->info.uid, &iw->infop->si_uid, Efault);
- unsafe_put_user(iw->info.status, &iw->infop->si_status, Efault);
- ret = true;
-done:
- user_write_access_end();
- return ret;
-Efault:
- ret = false;
- goto done;
+ return siginfo_put_user(iw->infop, &iw->info, signo);
}
static int io_waitid_finish(struct io_kiocb *req, int ret)
diff --git a/kernel/exit.c b/kernel/exit.c
index 1c9d1cbadcd0..e3a0b6699a23 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1723,6 +1723,28 @@ static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop,
return ret;
}
+bool siginfo_put_user(struct siginfo __user *infop, struct waitid_info *wi,
+ int signo)
+{
+ if (!infop)
+ return true;
+
+ if (!user_write_access_begin(infop, sizeof(*infop)))
+ return false;
+
+ unsafe_put_user(signo, &infop->si_signo, Efault);
+ unsafe_put_user(0, &infop->si_errno, Efault);
+ unsafe_put_user(wi->cause, &infop->si_code, Efault);
+ unsafe_put_user(wi->pid, &infop->si_pid, Efault);
+ unsafe_put_user(wi->uid, &infop->si_uid, Efault);
+ unsafe_put_user(wi->status, &infop->si_status, Efault);
+ user_write_access_end();
+ return true;
+Efault:
+ user_write_access_end();
+ return false;
+}
+
SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
infop, int, options, struct rusage __user *, ru)
{
@@ -1737,23 +1759,9 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
return -EFAULT;
}
- if (!infop)
- return err;
-
- if (!user_write_access_begin(infop, sizeof(*infop)))
+ if (siginfo_put_user(infop, &info, signo))
return -EFAULT;
-
- unsafe_put_user(signo, &infop->si_signo, Efault);
- unsafe_put_user(0, &infop->si_errno, Efault);
- unsafe_put_user(info.cause, &infop->si_code, Efault);
- unsafe_put_user(info.pid, &infop->si_pid, Efault);
- unsafe_put_user(info.uid, &infop->si_uid, Efault);
- unsafe_put_user(info.status, &infop->si_status, Efault);
- user_write_access_end();
return err;
-Efault:
- user_write_access_end();
- return -EFAULT;
}
long kernel_wait4(pid_t upid, int __user *stat_addr, int options,
diff --git a/kernel/exit.h b/kernel/exit.h
index f10207ba1341..b7e0e32133fa 100644
--- a/kernel/exit.h
+++ b/kernel/exit.h
@@ -27,4 +27,6 @@ long __do_wait(struct wait_opts *wo);
int kernel_waitid_prepare(struct wait_opts *wo, int which, pid_t upid,
struct waitid_info *infop, int options,
struct rusage *ru, unsigned int *f_flags);
+bool siginfo_put_user(struct siginfo __user *infop, struct waitid_info *wi,
+ int signo);
#endif
@@ -276,6 +276,8 @@ struct io_ring_ctx {
struct hlist_head futex_list;
struct io_alloc_cache futex_cache;
+ struct hlist_head waitid_list;
+
const struct cred *sq_creds; /* cred used for __io_sq_thread() */
struct io_sq_data *sq_data; /* if using sq thread polling */
@@ -66,6 +66,7 @@ struct io_uring_sqe {
__u32 msg_ring_flags;
__u32 uring_cmd_flags;
__u32 futex_flags;
+ __u32 waitid_flags;
};
__u64 user_data; /* data to be passed back at completion time */
/* pack this to avoid bogus arm OABI complaints */
@@ -239,6 +240,7 @@ enum io_uring_op {
IORING_OP_FUTEX_WAIT,
IORING_OP_FUTEX_WAKE,
IORING_OP_FUTEX_WAITV,
+ IORING_OP_WAITID,
/* this goes last, obviously */
IORING_OP_LAST,
@@ -8,6 +8,6 @@ obj-$(CONFIG_IO_URING) += io_uring.o xattr.o nop.o fs.o splice.o \
statx.o net.o msg_ring.o timeout.o \
sqpoll.o fdinfo.o tctx.o poll.o \
cancel.o kbuf.o rsrc.o rw.o opdef.o \
- notif.o
+ notif.o waitid.o
obj-$(CONFIG_IO_WQ) += io-wq.o
obj-$(CONFIG_FUTEX) += futex.o
@@ -16,6 +16,7 @@
#include "poll.h"
#include "timeout.h"
#include "futex.h"
+#include "waitid.h"
#include "cancel.h"
struct io_cancel {
@@ -124,6 +125,10 @@ int io_try_cancel(struct io_uring_task *tctx, struct io_cancel_data *cd,
if (ret != -ENOENT)
return ret;
+ ret = io_waitid_cancel(ctx, cd, issue_flags);
+ if (ret != -ENOENT)
+ return ret;
+
spin_lock(&ctx->completion_lock);
if (!(cd->flags & IORING_ASYNC_CANCEL_FD))
ret = io_timeout_cancel(ctx, cd);
@@ -93,6 +93,7 @@
#include "net.h"
#include "notif.h"
#include "futex.h"
+#include "waitid.h"
#include "timeout.h"
#include "poll.h"
@@ -336,6 +337,7 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
ctx->submit_state.free_list.next = NULL;
INIT_WQ_LIST(&ctx->locked_free_list);
INIT_HLIST_HEAD(&ctx->futex_list);
+ INIT_HLIST_HEAD(&ctx->waitid_list);
INIT_DELAYED_WORK(&ctx->fallback_work, io_fallback_req_func);
INIT_WQ_LIST(&ctx->submit_state.compl_reqs);
return ctx;
@@ -3259,6 +3261,7 @@ static __cold bool io_uring_try_cancel_requests(struct io_ring_ctx *ctx,
mutex_lock(&ctx->uring_lock);
ret |= io_poll_remove_all(ctx, task, cancel_all);
ret |= io_futex_remove_all(ctx, task, cancel_all);
+ ret |= io_waitid_remove_all(ctx, task, cancel_all);
mutex_unlock(&ctx->uring_lock);
ret |= io_kill_timeouts(ctx, task, cancel_all);
if (task)
@@ -34,6 +34,7 @@
#include "cancel.h"
#include "rw.h"
#include "futex.h"
+#include "waitid.h"
static int io_no_issue(struct io_kiocb *req, unsigned int issue_flags)
{
@@ -453,6 +454,10 @@ const struct io_issue_def io_issue_defs[] = {
.prep = io_eopnotsupp_prep,
#endif
},
+ [IORING_OP_WAITID] = {
+ .prep = io_waitid_prep,
+ .issue = io_waitid,
+ },
};
const struct io_cold_def io_cold_defs[] = {
@@ -681,6 +686,10 @@ const struct io_cold_def io_cold_defs[] = {
[IORING_OP_FUTEX_WAITV] = {
.name = "FUTEX_WAITV",
},
+ [IORING_OP_WAITID] = {
+ .name = "WAITID",
+ .async_size = sizeof(struct io_waitid_async),
+ },
};
const char *io_uring_get_opcode(u8 opcode)
new file mode 100644
@@ -0,0 +1,271 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Support for async notification of waitid
+ */
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/io_uring.h>
+
+#include <uapi/linux/io_uring.h>
+
+#include "io_uring.h"
+#include "cancel.h"
+#include "waitid.h"
+#include "../kernel/exit.h"
+
+struct io_waitid {
+ struct file *file;
+ int which;
+ pid_t upid;
+ int options;
+ struct wait_queue_head *head;
+ struct siginfo __user *infop;
+ struct waitid_info info;
+};
+
+static void io_waitid_free(struct io_kiocb *req)
+{
+ struct io_waitid_async *iwa = req->async_data;
+
+ put_pid(iwa->wo.wo_pid);
+ kfree(req->async_data);
+ req->async_data = NULL;
+ req->flags &= ~REQ_F_ASYNC_DATA;
+}
+
+static int io_waitid_finish(struct io_kiocb *req, int ret)
+{
+ struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);
+ int signo = 0;
+
+ if (ret > 0) {
+ signo = SIGCHLD;
+ ret = 0;
+ }
+ if (!iw->infop)
+ goto done;
+
+ if (!user_write_access_begin(iw->infop, sizeof(*iw->infop))) {
+ ret = -EFAULT;
+ goto done;
+ }
+
+ unsafe_put_user(signo, &iw->infop->si_signo, Efault);
+ unsafe_put_user(0, &iw->infop->si_errno, Efault);
+ unsafe_put_user(iw->info.cause, &iw->infop->si_code, Efault);
+ unsafe_put_user(iw->info.pid, &iw->infop->si_pid, Efault);
+ unsafe_put_user(iw->info.uid, &iw->infop->si_uid, Efault);
+ unsafe_put_user(iw->info.status, &iw->infop->si_status, Efault);
+done:
+ user_write_access_end();
+ io_waitid_free(req);
+ return ret;
+Efault:
+ ret = -EFAULT;
+ goto done;
+}
+
+static void io_waitid_complete(struct io_kiocb *req, int ret)
+{
+ struct io_tw_state ts = { .locked = true };
+
+ lockdep_assert_held(&req->ctx->uring_lock);
+
+ /*
+ * Did cancel find it meanwhile?
+ */
+ if (hlist_unhashed(&req->hash_node))
+ return;
+
+ hlist_del_init(&req->hash_node);
+
+ ret = io_waitid_finish(req, ret);
+ if (ret < 0)
+ req_set_fail(req);
+ io_req_set_res(req, ret, 0);
+ io_req_task_complete(req, &ts);
+}
+
+static bool __io_waitid_cancel(struct io_ring_ctx *ctx, struct io_kiocb *req)
+{
+ struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);
+ struct wait_queue_head *head;
+
+ head = READ_ONCE(iw->head);
+ if (head) {
+ struct io_waitid_async *iwa = req->async_data;
+
+ spin_lock_irq(&head->lock);
+ list_del_init(&iwa->wo.child_wait.entry);
+ iw->head = NULL;
+ spin_unlock_irq(&head->lock);
+ io_waitid_complete(req, -ECANCELED);
+ return true;
+ }
+
+ return false;
+}
+
+int io_waitid_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd,
+ unsigned int issue_flags)
+{
+ struct hlist_node *tmp;
+ struct io_kiocb *req;
+ int nr = 0;
+
+ if (cd->flags & (IORING_ASYNC_CANCEL_FD|IORING_ASYNC_CANCEL_FD_FIXED))
+ return -ENOENT;
+
+ io_ring_submit_lock(ctx, issue_flags);
+ hlist_for_each_entry_safe(req, tmp, &ctx->waitid_list, hash_node) {
+ if (req->cqe.user_data != cd->data &&
+ !(cd->flags & IORING_ASYNC_CANCEL_ANY))
+ continue;
+ if (__io_waitid_cancel(ctx, req))
+ nr++;
+ if (!(cd->flags & IORING_ASYNC_CANCEL_ALL))
+ break;
+ }
+ io_ring_submit_unlock(ctx, issue_flags);
+
+ if (nr)
+ return nr;
+
+ return -ENOENT;
+}
+
+bool io_waitid_remove_all(struct io_ring_ctx *ctx, struct task_struct *task,
+ bool cancel_all)
+{
+ struct hlist_node *tmp;
+ struct io_kiocb *req;
+ bool found = false;
+
+ lockdep_assert_held(&ctx->uring_lock);
+
+ hlist_for_each_entry_safe(req, tmp, &ctx->waitid_list, hash_node) {
+ if (!io_match_task_safe(req, task, cancel_all))
+ continue;
+ __io_waitid_cancel(ctx, req);
+ found = true;
+ }
+
+ return found;
+}
+
+static void io_waitid_cb(struct io_kiocb *req, struct io_tw_state *ts)
+{
+ struct io_waitid_async *iwa = req->async_data;
+ struct io_ring_ctx *ctx = req->ctx;
+ int ret;
+
+ /*
+ * If we get -ERESTARTSYS here, we need to re-arm and check again
+ * to ensure we get another callback. If the retry works, then we can
+ * just remove ourselves from the waitqueue again and finish the
+ * request.
+ */
+ ret = __do_wait(&iwa->wo);
+ if (unlikely(ret == -ERESTARTSYS)) {
+ struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);
+
+ io_tw_lock(ctx, ts);
+ iw->head = ¤t->signal->wait_chldexit;
+ add_wait_queue(iw->head, &iwa->wo.child_wait);
+ ret = __do_wait(&iwa->wo);
+ if (ret == -ERESTARTSYS)
+ return;
+
+ remove_wait_queue(iw->head, &iwa->wo.child_wait);
+ iw->head = NULL;
+ }
+
+ io_tw_lock(ctx, ts);
+ io_waitid_complete(req, ret);
+}
+
+static int io_waitid_wait(struct wait_queue_entry *wait, unsigned mode,
+ int sync, void *key)
+{
+ struct wait_opts *wo = container_of(wait, struct wait_opts, child_wait);
+ struct io_waitid_async *iwa = container_of(wo, struct io_waitid_async, wo);
+ struct io_kiocb *req = iwa->req;
+ struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);
+ struct task_struct *p = key;
+
+ if (!pid_child_should_wake(wo, p))
+ return 0;
+
+ req->io_task_work.func = io_waitid_cb;
+ io_req_task_work_add(req);
+ iw->head = NULL;
+ list_del_init(&wait->entry);
+ return 1;
+}
+
+int io_waitid_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+ struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);
+
+ if (sqe->addr || sqe->buf_index || sqe->addr3 || sqe->waitid_flags)
+ return -EINVAL;
+
+ iw->which = READ_ONCE(sqe->len);
+ iw->options = READ_ONCE(sqe->file_index);
+ iw->upid = READ_ONCE(sqe->fd);
+ iw->infop = u64_to_user_ptr(READ_ONCE(sqe->addr2));
+ iw->head = NULL;
+ return 0;
+}
+
+int io_waitid(struct io_kiocb *req, unsigned int issue_flags)
+{
+ struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid);
+ struct io_ring_ctx *ctx = req->ctx;
+ struct io_waitid_async *iwa;
+ unsigned int f_flags = 0;
+ int ret;
+
+ if (io_alloc_async_data(req))
+ return -ENOMEM;
+
+ iwa = req->async_data;
+ iwa->req = req;
+
+ ret = kernel_waitid_prepare(&iwa->wo, iw->which, iw->upid, &iw->info,
+ iw->options, NULL, &f_flags);
+ if (ret)
+ goto done;
+
+ /*
+ * Arm our callback and add us to the waitqueue, in case no events
+ * are available.
+ */
+ init_waitqueue_func_entry(&iwa->wo.child_wait, io_waitid_wait);
+ iwa->wo.child_wait.private = req->task;
+ iw->head = ¤t->signal->wait_chldexit;
+ add_wait_queue(iw->head, &iwa->wo.child_wait);
+
+ io_ring_submit_lock(ctx, issue_flags);
+ hlist_add_head(&req->hash_node, &ctx->waitid_list);
+
+ ret = __do_wait(&iwa->wo);
+ if (ret == -ERESTARTSYS) {
+ io_ring_submit_unlock(ctx, issue_flags);
+ return IOU_ISSUE_SKIP_COMPLETE;
+ }
+
+ hlist_del_init(&req->hash_node);
+ remove_wait_queue(iw->head, &iwa->wo.child_wait);
+ iw->head = NULL;
+ ret = io_waitid_finish(req, ret);
+
+ io_ring_submit_unlock(ctx, issue_flags);
+done:
+ if (ret < 0)
+ req_set_fail(req);
+ io_req_set_res(req, ret, 0);
+ return IOU_OK;
+}
new file mode 100644
@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "../kernel/exit.h"
+
+struct io_waitid_async {
+ struct io_kiocb *req;
+ struct wait_opts wo;
+};
+
+int io_waitid_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_waitid(struct io_kiocb *req, unsigned int issue_flags);
+int io_waitid_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd,
+ unsigned int issue_flags);
+bool io_waitid_remove_all(struct io_ring_ctx *ctx, struct task_struct *task,
+ bool cancel_all);