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From:   Amit Klein <aksecurity@gmail.com>
Date:   Fri, 18 Jun 2021 12:53:33 +0300
Message-ID: <CANEQ_+JwAvcHFN__41-QxTSqXo7RfDLbTZ-t3S51zsyqkpw=PQ@mail.gmail.com>
Subject: Re: [PATCH 5.4 175/244] inet: use bigger hash table for IP ID generation
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        Eric Dumazet <edumazet@google.com>, Willy Tarreau <w@1wt.eu>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
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I just submitted a revised patch for 4.14. Sorry for the earlier blunder.

On Wed, Jun 16, 2021 at 5:56 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Wed, Jun 16, 2021 at 12:16:52PM +0300, Amit Klein wrote:
> > Here is the patch (minus headers, description, etc. - I believe these
> > can be copied as is from the 5.x patch, but not sure about the
> > rules...). It can be applied to 4.14.236. If this is OK, I can move on
> > to 4.9 and 4.4.
> >
> >
> >  net/ipv4/route.c | 41 ++++++++++++++++++++++++++++-------------
> >  1 file changed, 28 insertions(+), 13 deletions(-)
> >
> > diff --git a/net/ipv4/route.c b/net/ipv4/route.c
> > index 78d6bc61a1d8..022a2b748da3 100644
> > --- a/net/ipv4/route.c
> > +++ b/net/ipv4/route.c
> > @@ -70,6 +70,7 @@
> >  #include <linux/types.h>
> >  #include <linux/kernel.h>
> >  #include <linux/mm.h>
> > +#include <linux/memblock.h>
> >  #include <linux/string.h>
> >  #include <linux/socket.h>
> >  #include <linux/sockios.h>
> > @@ -485,8 +486,10 @@ static void ipv4_confirm_neigh(const struct
> > dst_entry *dst, const void *daddr)
> >      __ipv4_confirm_neigh(dev, *(__force u32 *)pkey);
> >  }
> >
> > -#define IP_IDENTS_SZ 2048u
> > -
> > +/* Hash tables of size 2048..262144 depending on RAM size.
> > + * Each bucket uses 8 bytes.
> > + */
> > +static u32 ip_idents_mask __read_mostly;
> >  static atomic_t *ip_idents __read_mostly;
> >  static u32 *ip_tstamps __read_mostly;
> >
> > @@ -496,12 +499,16 @@ static u32 *ip_tstamps __read_mostly;
> >   */
> >  u32 ip_idents_reserve(u32 hash, int segs)
> >  {
> > -    u32 *p_tstamp = ip_tstamps + hash % IP_IDENTS_SZ;
> > -    atomic_t *p_id = ip_idents + hash % IP_IDENTS_SZ;
> > -    u32 old = ACCESS_ONCE(*p_tstamp);
> > -    u32 now = (u32)jiffies;
> > +    u32 bucket, old, now = (u32)jiffies;
> > +    atomic_t *p_id;
> > +    u32 *p_tstamp;
>
> Your patch is corrupted and couldn't be applied if I wanted to :(
>