From: Jesper Juhl Subject: Re: [PATCH] In crypto_add_alg(), 'exact' wants to be initialized to 0 Date: Wed, 1 Feb 2012 21:36:13 +0100 (CET) Message-ID: References: Mime-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="8323328-1028546279-1328128573=:8577" Cc: Herbert Xu , "David S. Miller" , linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, Steffen Klassert To: "devendra.aaru" Return-path: Received: from swampdragon.chaosbits.net ([90.184.90.115]:19841 "EHLO swampdragon.chaosbits.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752039Ab2BAUfx (ORCPT ); Wed, 1 Feb 2012 15:35:53 -0500 In-Reply-To: Sender: linux-crypto-owner@vger.kernel.org List-ID: This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323328-1028546279-1328128573=:8577 Content-Type: TEXT/PLAIN; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT On Wed, 1 Feb 2012, Jesper Juhl wrote: > On Wed, 1 Feb 2012, devendra.aaru wrote: > > > On Sun, Jan 29, 2012 at 5:39 PM, Jesper Juhl wrote: > > > We declare 'exact' without initializing it and then do: > > > > > > [...] > > > ? ? ? ?if (strlen(p->cru_driver_name)) > > > ? ? ? ? ? ? ? ?exact = 1; > > > > > > ? ? ? ?if (priority && !exact) > > > ? ? ? ? ? ? ? ?return -EINVAL; > > > > > > [...] > > > > > > If the first 'if' is not true, then the second will test an > > > uninitialized 'exact'. > > > > not needed . as the cru_driver_name will always be present :). > > If that is indeed the case, and we are guaranteed that, then it would seem > that a patch like the following would be what we want instead?? > > Please note that this patch is intended just for discussion, nothing else > (which is why I left out a Signed-off-by on purpose), since I've not > tested it beyond checking that it compiles, nor have I verified your claim > that cru_driver_name will always be present. > > Herbert, David, any input? > > > Subject: [PATCH] Simplify crypto_add_alg() and crypto_alg_match() > > Since cru_driver_name will always be present, the test > > if (strlen(p->cru_driver_name)) > exact = 1; > > will always be true. So there's no need to have the test at all, we > can just unconditionally assign 1 to 'exact'. > > And if 'exact' is always 1, then we'll never take the true branch of > > if (priority && !exact) > return -EINVAL; > > so we may as well just remove those two lines completely. > > At this point we may as well just remove 'exact' entirely and just use > a hardcoded 1 in the call to crypto_alg_match(). > > The 'name' variable is also entirely redundant since with > cru_driver_name always being present we'll always take the first > branch in > > if (strlen(p->cru_driver_name)) > name = p->cru_driver_name; > else > name = p->cru_name; > > and then we may as well just use 'p->cru_driver_name' itself the one > place where it is needed in the call to crypto_alg_mod_lookup(). > > At this point all calls to the static crypto_alg crypto_alg_match() > function pass 1 as the second argument, so there's not really any > point any more in that function having that argument, so let's remove > it and the code that tests it. > > And since strlen(p->cru_driver_name) will also always be true in that > function, we can simplify the assignment to 'match'. > > --- > crypto/crypto_user.c | 33 ++++++++------------------------- > 1 files changed, 8 insertions(+), 25 deletions(-) > > diff --git a/crypto/crypto_user.c b/crypto/crypto_user.c > index 16f8693..7760c22 100644 > --- a/crypto/crypto_user.c > +++ b/crypto/crypto_user.c > @@ -38,23 +38,19 @@ struct crypto_dump_info { > u16 nlmsg_flags; > }; > > -static struct crypto_alg *crypto_alg_match(struct crypto_user_alg *p, int exact) > +static struct crypto_alg *crypto_alg_match(struct crypto_user_alg *p) > { > struct crypto_alg *q, *alg = NULL; > > down_read(&crypto_alg_sem); > > list_for_each_entry(q, &crypto_alg_list, cra_list) { > - int match = 0; > + int match; > > if ((q->cra_flags ^ p->cru_type) & p->cru_mask) > continue; > > - if (strlen(p->cru_driver_name)) > - match = !strcmp(q->cra_driver_name, > - p->cru_driver_name); > - else if (!exact) > - match = !strcmp(q->cra_name, p->cru_name); > + match = !strcmp(q->cra_driver_name, p->cru_driver_name); > > if (match) { Actually, we could just get rid of 'match' entirely as well and just do if (!strcmp(q->cra_driver_name, p->cru_driver_name)) { > alg = q; > @@ -195,7 +191,7 @@ static int crypto_report(struct sk_buff *in_skb, struct nlmsghdr *in_nlh, > if (!p->cru_driver_name) > return -EINVAL; > > - alg = crypto_alg_match(p, 1); > + alg = crypto_alg_match(p); > if (!alg) > return -ENOENT; > > @@ -259,7 +255,7 @@ static int crypto_update_alg(struct sk_buff *skb, struct nlmsghdr *nlh, > if (priority && !strlen(p->cru_driver_name)) > return -EINVAL; > > - alg = crypto_alg_match(p, 1); > + alg = crypto_alg_match(p); > if (!alg) > return -ENOENT; > > @@ -283,7 +279,7 @@ static int crypto_del_alg(struct sk_buff *skb, struct nlmsghdr *nlh, > struct crypto_alg *alg; > struct crypto_user_alg *p = nlmsg_data(nlh); > > - alg = crypto_alg_match(p, 1); > + alg = crypto_alg_match(p); > if (!alg) > return -ENOENT; > > @@ -304,28 +300,15 @@ static int crypto_del_alg(struct sk_buff *skb, struct nlmsghdr *nlh, > static int crypto_add_alg(struct sk_buff *skb, struct nlmsghdr *nlh, > struct nlattr **attrs) > { > - int exact; > - const char *name; > struct crypto_alg *alg; > struct crypto_user_alg *p = nlmsg_data(nlh); > struct nlattr *priority = attrs[CRYPTOCFGA_PRIORITY_VAL]; > > - if (strlen(p->cru_driver_name)) > - exact = 1; > - > - if (priority && !exact) > - return -EINVAL; > - > - alg = crypto_alg_match(p, exact); > + alg = crypto_alg_match(p); > if (alg) > return -EEXIST; > > - if (strlen(p->cru_driver_name)) > - name = p->cru_driver_name; > - else > - name = p->cru_name; > - > - alg = crypto_alg_mod_lookup(name, p->cru_type, p->cru_mask); > + alg = crypto_alg_mod_lookup(p->cru_driver_name, p->cru_type, p->cru_mask); > if (IS_ERR(alg)) > return PTR_ERR(alg); > > -- Jesper Juhl http://www.chaosbits.net/ Don't top-post http://www.catb.org/jargon/html/T/top-post.html Plain text mails only, please. --8323328-1028546279-1328128573=:8577--