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Date:   Wed, 23 Dec 2020 11:36:23 +0100
From:   Stefano Garzarella <sgarzare@redhat.com>
To:     Yejune Deng <yejune.deng@gmail.com>
Cc:     viro@zeniv.linux.org.uk, axboe@kernel.dk,
        linux-fsdevel@vger.kernel.org, io-uring@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] io_uring: remove io_remove_personalities()
Message-ID: <20201223103623.mxjsmitdmqsx6ftd@steredhat>
References: <1608694025-121050-1-git-send-email-yejune.deng@gmail.com>
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On Wed, Dec 23, 2020 at 11:27:05AM +0800, Yejune Deng wrote:
>The function io_remove_personalities() is very similar to
>io_unregister_personality(),but the latter has a more reasonable
>return value.
>
>Signed-off-by: Yejune Deng <yejune.deng@gmail.com>
>---
> fs/io_uring.c | 25 ++++++-------------------
> 1 file changed, 6 insertions(+), 19 deletions(-)

The patch LGTM, maybe as an alternative you can leave 
io_remove_personality() with the interface needed by idr_for_each() and 
implement io_unregister_personality() calling io_remove_personality() 
with the right parameters.

Just an idea, but I'm also fine with this patch, so:

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

>
>diff --git a/fs/io_uring.c b/fs/io_uring.c
>index b749578..000ea9a 100644
>--- a/fs/io_uring.c
>+++ b/fs/io_uring.c
>@@ -8608,7 +8608,7 @@ static int io_uring_fasync(int fd, struct file *file, int on)
> 	return fasync_helper(fd, file, on, &ctx->cq_fasync);
> }
>
>-static int io_remove_personalities(int id, void *p, void *data)
>+static int io_unregister_personality(int id, void *p, void *data)
> {
> 	struct io_ring_ctx *ctx = data;
> 	struct io_identity *iod;
>@@ -8618,8 +8618,10 @@ static int io_remove_personalities(int id, void *p, void *data)
> 		put_cred(iod->creds);
> 		if (refcount_dec_and_test(&iod->count))
> 			kfree(iod);
>+		return 0;
> 	}
>-	return 0;
>+
>+	return -EINVAL;
> }
>
> static void io_ring_exit_work(struct work_struct *work)
>@@ -8657,7 +8659,7 @@ static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx)
>
> 	/* if we failed setting up the ctx, we might not have any rings */
> 	io_iopoll_try_reap_events(ctx);
>-	idr_for_each(&ctx->personality_idr, io_remove_personalities, ctx);
>+	idr_for_each(&ctx->personality_idr, io_unregister_personality, ctx);
>
> 	/*
> 	 * Do this upfront, so we won't have a grace period where the ring
>@@ -9679,21 +9681,6 @@ static int io_register_personality(struct io_ring_ctx *ctx)
> 	return ret;
> }
>
>-static int io_unregister_personality(struct io_ring_ctx *ctx, unsigned id)
>-{
>-	struct io_identity *iod;
>-
>-	iod = idr_remove(&ctx->personality_idr, id);
>-	if (iod) {
>-		put_cred(iod->creds);
>-		if (refcount_dec_and_test(&iod->count))
>-			kfree(iod);
>-		return 0;
>-	}
>-
>-	return -EINVAL;
>-}
>-
> static int io_register_restrictions(struct io_ring_ctx *ctx, void __user *arg,
> 				    unsigned int nr_args)
> {
>@@ -9906,7 +9893,7 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
> 		ret = -EINVAL;
> 		if (arg)
> 			break;
>-		ret = io_unregister_personality(ctx, nr_args);
>+		ret = io_unregister_personality(nr_args, NULL, ctx);
> 		break;
> 	case IORING_REGISTER_ENABLE_RINGS:
> 		ret = -EINVAL;
>-- 
>1.9.1
>