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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Mon, 6 Mar 2023 10:48:04 -0800
Message-ID: <CAHk-=wj73=Os1p=W7D2va=Rd81ZKvjb35yWgXQNgn1hXNRpAbw@mail.gmail.com>
Subject: Re: [PATCH 3/5] scsi: lpfc: fix lpfc_cpu_affinity_check() if no
 further cpus set
To:     Vernon Yang <vernon2gm@gmail.com>
Cc:     tytso@mit.edu, Jason@zx2c4.com, davem@davemloft.net,
        edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
        jejb@linux.ibm.com, martin.petersen@oracle.com,
        yury.norov@gmail.com, andriy.shevchenko@linux.intel.com,
        linux@rasmusvillemoes.dk, james.smart@broadcom.com,
        dick.kennedy@broadcom.com, linux-kernel@vger.kernel.org,
        wireguard@lists.zx2c4.com, netdev@vger.kernel.org,
        linux-scsi@vger.kernel.org
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On Mon, Mar 6, 2023 at 8:07=E2=80=AFAM Vernon Yang <vernon2gm@gmail.com> wr=
ote:
>
> -                               if (new_cpu =3D=3D nr_cpumask_bits)
> +                               if (new_cpu >=3D nr_cpumask_bits)

This all should use "nr_cpu_ids", not "nr_cpumask_bits".

But I really suspect that it should all be rewritten to not do that
thing over and over, but just use a helper function for it.

  int lpfc_next_present_cpu(int n, int alternate)
  {
        n =3D cpumask_next(n, cpu_present_mask);
        if (n >=3D nr_cpu_ids)
                n =3D alternate;
        return n;
  }

and then you could just use

        start_cpu =3D lpfc_next_present_cpu(new_cpu, first_cpu);

or similar.

              Linus

PS. We "kind of" already have a helper function for this:
cpumask_next_wrap(). But it's really meant for a different pattern
entirely, so let's not confuse things.