From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 604D7CE7A81 for ; Mon, 25 Sep 2023 08:49:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=oiJOP5F+SIwEZJckiK3NvEP2CBv+KW/NgffMoWj+jtk=; b=3oS0WQXDyVvv4a u5vo8tO/IyiXTn3US7TVUVtS4Cj+ZRix1EvOqMIl77JnP0+q1xG65ut70TUUIMlRn0pBDs5AiGVLA GvcTNT1q3KN0vhhVKeTse9xisb/+ymmzQLqhLgqUZ7GPr67TvG+CO4AIfRnLViVAO1kogADFyi+gu EYNpEASB2LujKGLdtveQO2ue9n3K+yOeafcW5ViPt19bKnqrqiP/pAKntbSCYy04a11EsTt4UPyrw 3BwRbBoDVUvKr7sKb+NtjUsFjaWmoTtzprHjvUh/ePF6LHcGFussaJxE9ukLJaFYQttBLOCg5lyF9 8dEJl5m09FDsbJUwyi6g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qkhHp-00Dly9-2t; Mon, 25 Sep 2023 08:49:49 +0000 Received: from relay9-d.mail.gandi.net ([2001:4b98:dc4:8::229]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qkhHm-00Dlx2-1g for linux-mtd@lists.infradead.org; Mon, 25 Sep 2023 08:49:48 +0000 Received: by mail.gandi.net (Postfix) with ESMTPSA id 19B2CFF803; Mon, 25 Sep 2023 08:49:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1695631782; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=INBNCslwxKAO9zA0oLb6M4ySYAmug40tgKE1H/MmE0A=; b=TYej/Qhs2tQt0X2X/1RpcZsO4PzpvkrHD6BxUtce/kqEyax4ZxRj1S/sEYcWjqB0CO7TOK HwaElyLLqzCZdL56EkdOOuZy6SXYGOEK7VBY9yirkxT/jTHZdITbC7qWW9+K1T9RHH3PMY JsKw3fQpnhmU+Xi8dCW88Y/WNNrhqDjfBoyZiz9uJtT04NQiy3CvxGZo3g9QC9utv3rz26 grC+poafNhzfdTSS1R2PAgHR3MPF/KLR++jSqhXpz+P9tjBLbQLmhAJZtg7fznHcedhviv yQzPzPnn6QubeEZoxgSR9rRNwUqgUaHQ5DkaCsZHYycaOk1f1VBRO/ouHIH81Q== Date: Mon, 25 Sep 2023 10:49:38 +0200 From: Miquel Raynal To: ZhaoLong Wang Cc: , , , , , , Subject: Re: [RFC] mtd: Fix error code loss in mtdchar_read() function. Message-ID: <20230925104938.3f7b4284@xps-13> In-Reply-To: <20230923005856.2538223-1-wangzhaolong1@huawei.com> References: <20230923005856.2538223-1-wangzhaolong1@huawei.com> Organization: Bootlin X-Mailer: Claws Mail 4.0.0 (GTK+ 3.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 X-GND-Sasl: miquel.raynal@bootlin.com X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230925_014946_996248_B2198BD1 X-CRM114-Status: GOOD ( 22.92 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org SGVsbG8sCgpSaWNoYXJkLCB5b3VyIGFkdmljZSBpcyB3ZWxjb21lIGhlcmUuCgp3YW5nemhhb2xv bmcxQGh1YXdlaS5jb20gd3JvdGUgb24gU2F0LCAyMyBTZXAgMjAyMyAwODo1ODo1NiArMDgwMDoK Cj4gSW4gdGhlIGZpcnN0IHdoaWxlIGxvb3AsIGlmIHRoZSBtdGRfcmVhZCgpIGZ1bmN0aW9uIHJl dHVybnMgLUVCQURNU0cKCgkJCSAgICAgIHMvdGhlLy8JICAgICBzL2Z1bmN0aW9uLy8KCQkJICAg ICAgLAoKPiBhbmQgJ3JldGxlbicgcmV0dXJucyAwLCB0aGUgbG9vcCBicmVhayBhbmQgdGhlIGZ1 bmN0aW9uIHJldHVybnMgdmFsdWUKCnMvYW5kLy8JCXJlbWFpbnMgdG8gMC4gVGhlIGxvb3AgYnJl YWtzIGFuZCB0aGUgZnVuY3Rpb24KcmV0dXJucyAndG90YWxfcmV0bGVuJyB3aGljaCBpcyAwIGlu c3RlYWQgb2YgdGhlIGVycm9yIGNvZGUuCgo+ICd0b3RhbF9yZXRsZW4nIGlzIDAsIG5vdCB0aGUg ZXJyb3IgY29kZS4KCkFjdHVhbGx5IGFmdGVyIGxvb2tpbmcgYXQgdGhlIGNvZGUsIEkgaGF2ZSBu byBzdHJvbmcgb3BpbmlvbgpyZWdhcmRpbmcgd2hldGhlciB3ZSBzaG91bGQgcmV0dXJuIDAgb3Ig YW4gZXJyb3IgY29kZSBpbiB0aGlzIGNhc2UuIAoKVGhlcmUgaXMgdGhpcyBjb21tZW50IHJpZ2h0 IGFib3ZlLCBhbmQgSSdtIG5vdCBzdXJlIGl0IGlzIHN0aWxsIHVwIHRvCmRhdGUgYmVjYXVzZSBJ IGJlbGlldmUgbWFueSBkcml2ZXJzIGp1c3QgZG9uJ3QgcHJvdmlkZSB0aGUgZGF0YSB1cG9uCkVD QyBlcnJvcjoKCiAgICAgICAgICAgICAgICAvKiBOYW5kIHJldHVybnMgLUVCQURNU0cgb24gRUND IGVycm9ycywgYnV0IGl0IHJldHVybnMKICAgICAgICAgICAgICAgICAqIHRoZSBkYXRhLiBGb3Ig b3VyIHVzZXJzcGFjZSB0b29scyBpdCBpcyBpbXBvcnRhbnQKICAgICAgICAgICAgICAgICAqIHRv IGR1bXAgYXJlYXMgd2l0aCBFQ0MgZXJyb3JzIQogICAgICAgICAgICAgICAgICogRm9yIGtlcm5l bCBpbnRlcm5hbCB1c2FnZSBpdCBhbHNvIG1pZ2h0IHJldHVybiAtRVVDTEVBTgogICAgICAgICAg ICAgICAgICogdG8gc2lnbmFsIHRoZSBjYWxsZXIgdGhhdCBhIGJpdGZsaXAgaGFzIG9jY3VycmVk IGFuZCBoYXMKICAgICAgICAgICAgICAgICAqIGJlZW4gY29ycmVjdGVkIGJ5IHRoZSBFQ0MgYWxn b3JpdGhtLgogICAgICAgICAgICAgICAgICogVXNlcnNwYWNlIHNvZnR3YXJlIHdoaWNoIGFjY2Vz c2VzIE5BTkQgdGhpcyB3YXkKICAgICAgICAgICAgICAgICAqIG11c3QgYmUgYXdhcmUgb2YgdGhl IGZhY3QgdGhhdCBpdCBkZWFscyB3aXRoIE5BTkQKICAgICAgICAgICAgICAgICAqLwoKPiBUaGlz IHByb2JsZW0gY2F1c2VzIHRoZSB1c2VyLXNwYWNlIHByb2dyYW0gdG8gZW5jb3VudGVyIEVPRiB3 aGVuIGl0IGhhcwo+IG5vdCBmaW5pc2hlZCByZWFkaW5nIHRoZSBtdGQgcGFydGlvbiwgYW5kIHRo aXMgYWxzbyB2aW9sYXRlcyB0aGUgcmVhZAo+IHN5c3RlbSBjYWxsIHN0YW5kYXJkIGluIFBPU0lY Lgo+IAo+IExpbms6IGh0dHBzOi8vYnVnemlsbGEua2VybmVsLm9yZy9zaG93X2J1Zy5jZ2k/aWQ9 MjE3OTM5Cj4gU2lnbmVkLW9mZi1ieTogWmhhb0xvbmcgV2FuZyA8d2FuZ3poYW9sb25nMUBodWF3 ZWkuY29tPgo+IC0tLQo+ICBkcml2ZXJzL210ZC9tdGRjaGFyLmMgfCAyICstCj4gIDEgZmlsZSBj aGFuZ2VkLCAxIGluc2VydGlvbigrKSwgMSBkZWxldGlvbigtKQo+IAo+IGRpZmYgLS1naXQgYS9k cml2ZXJzL210ZC9tdGRjaGFyLmMgYi9kcml2ZXJzL210ZC9tdGRjaGFyLmMKPiBpbmRleCA4ZGM0 ZjVjNDkzZmMuLmJhNjBkYzZiZWY5OCAxMDA2NDQKPiAtLS0gYS9kcml2ZXJzL210ZC9tdGRjaGFy LmMKPiArKysgYi9kcml2ZXJzL210ZC9tdGRjaGFyLmMKPiBAQCAtMjExLDcgKzIxMSw3IEBAIHN0 YXRpYyBzc2l6ZV90IG10ZGNoYXJfcmVhZChzdHJ1Y3QgZmlsZSAqZmlsZSwgY2hhciBfX3VzZXIg KmJ1Ziwgc2l6ZV90IGNvdW50LAo+ICAJfQo+ICAKPiAgCWtmcmVlKGtidWYpOwo+IC0JcmV0dXJu IHRvdGFsX3JldGxlbjsKPiArCXJldHVybiB0b3RhbF9yZXRsZW4gPyB0b3RhbF9yZXRsZW4gOiBy ZXQ7CgpUaGlzIGlzIGtpbmQgb2Ygd3JvbmcsIGlmIHJldCBpcyAwIHRoZW4geW91IHJldHVybiBy ZXQgd2hpbGUgeW91IHNob3VsZApyZXR1cm4gdG90YWxfcmV0bGVuLiBJbiBwcmFjdGljZSBpdCBk b2VzIG5vdCByZWFsbHkgbWF0dGVyLCB0aGUgcmVzdWx0CmlzIHRoZSBzYW1lLCBidXQgaXQgbWFr ZXMgaXQgaGFyZGVyIHRvIHVuZGVyc3RhbmQgdGhlIGNvZGUgSU1ITy4KCj4gIH0gLyogbXRkY2hh cl9yZWFkICovCj4gIAo+ICBzdGF0aWMgc3NpemVfdCBtdGRjaGFyX3dyaXRlKHN0cnVjdCBmaWxl ICpmaWxlLCBjb25zdCBjaGFyIF9fdXNlciAqYnVmLCBzaXplX3QgY291bnQsCgoKVGhhbmtzLApN aXF1w6hsCgpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX18KTGludXggTVREIGRpc2N1c3Npb24gbWFpbGluZyBsaXN0Cmh0dHA6Ly9saXN0cy5pbmZy YWRlYWQub3JnL21haWxtYW4vbGlzdGluZm8vbGludXgtbXRkLwo= From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22541CE7A81 for ; Mon, 25 Sep 2023 08:49:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233074AbjIYIt4 (ORCPT ); Mon, 25 Sep 2023 04:49:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37030 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232979AbjIYItv (ORCPT ); Mon, 25 Sep 2023 04:49:51 -0400 Received: from relay9-d.mail.gandi.net (relay9-d.mail.gandi.net [IPv6:2001:4b98:dc4:8::229]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E14C1D3 for ; Mon, 25 Sep 2023 01:49:43 -0700 (PDT) Received: by mail.gandi.net (Postfix) with ESMTPSA id 19B2CFF803; Mon, 25 Sep 2023 08:49:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1695631782; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=INBNCslwxKAO9zA0oLb6M4ySYAmug40tgKE1H/MmE0A=; b=TYej/Qhs2tQt0X2X/1RpcZsO4PzpvkrHD6BxUtce/kqEyax4ZxRj1S/sEYcWjqB0CO7TOK HwaElyLLqzCZdL56EkdOOuZy6SXYGOEK7VBY9yirkxT/jTHZdITbC7qWW9+K1T9RHH3PMY JsKw3fQpnhmU+Xi8dCW88Y/WNNrhqDjfBoyZiz9uJtT04NQiy3CvxGZo3g9QC9utv3rz26 grC+poafNhzfdTSS1R2PAgHR3MPF/KLR++jSqhXpz+P9tjBLbQLmhAJZtg7fznHcedhviv yQzPzPnn6QubeEZoxgSR9rRNwUqgUaHQ5DkaCsZHYycaOk1f1VBRO/ouHIH81Q== Date: Mon, 25 Sep 2023 10:49:38 +0200 From: Miquel Raynal To: ZhaoLong Wang Cc: , , , , , , Subject: Re: [RFC] mtd: Fix error code loss in mtdchar_read() function. Message-ID: <20230925104938.3f7b4284@xps-13> In-Reply-To: <20230923005856.2538223-1-wangzhaolong1@huawei.com> References: <20230923005856.2538223-1-wangzhaolong1@huawei.com> Organization: Bootlin X-Mailer: Claws Mail 4.0.0 (GTK+ 3.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-GND-Sasl: miquel.raynal@bootlin.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Richard, your advice is welcome here. wangzhaolong1@huawei.com wrote on Sat, 23 Sep 2023 08:58:56 +0800: > In the first while loop, if the mtd_read() function returns -EBADMSG s/the// s/function// , > and 'retlen' returns 0, the loop break and the function returns value s/and// remains to 0. The loop breaks and the function returns 'total_retlen' which is 0 instead of the error code. > 'total_retlen' is 0, not the error code. Actually after looking at the code, I have no strong opinion regarding whether we should return 0 or an error code in this case.=20 There is this comment right above, and I'm not sure it is still up to date because I believe many drivers just don't provide the data upon ECC error: /* Nand returns -EBADMSG on ECC errors, but it returns * the data. For our userspace tools it is important * to dump areas with ECC errors! * For kernel internal usage it also might return -EUCLEAN * to signal the caller that a bitflip has occurred and has * been corrected by the ECC algorithm. * Userspace software which accesses NAND this way * must be aware of the fact that it deals with NAND */ > This problem causes the user-space program to encounter EOF when it has > not finished reading the mtd partion, and this also violates the read > system call standard in POSIX. >=20 > Link: https://bugzilla.kernel.org/show_bug.cgi?id=3D217939 > Signed-off-by: ZhaoLong Wang > --- > drivers/mtd/mtdchar.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) >=20 > diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c > index 8dc4f5c493fc..ba60dc6bef98 100644 > --- a/drivers/mtd/mtdchar.c > +++ b/drivers/mtd/mtdchar.c > @@ -211,7 +211,7 @@ static ssize_t mtdchar_read(struct file *file, char _= _user *buf, size_t count, > } > =20 > kfree(kbuf); > - return total_retlen; > + return total_retlen ? total_retlen : ret; This is kind of wrong, if ret is 0 then you return ret while you should return total_retlen. In practice it does not really matter, the result is the same, but it makes it harder to understand the code IMHO. > } /* mtdchar_read */ > =20 > static ssize_t mtdchar_write(struct file *file, const char __user *buf, = size_t count, Thanks, Miqu=C3=A8l