linux-kernel - Re: [Patch 1/2] tools/memory-model: Update some warning labels

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Message-ID: <16ca40c7-ba9d-6741-e7fc-fd553c80a757@huaweicloud.com>
Date:   Wed, 25 Jan 2023 21:35:44 +0100
From:   Jonas Oberhauser <jonas.oberhauser@...weicloud.com>
To:     Alan Stern <stern@...land.harvard.edu>,
        "Paul E. McKenney" <paulmck@...nel.org>
Cc:     Andrea Parri <parri.andrea@...il.com>,
        Jonas Oberhauser <jonas.oberhauser@...wei.com>,
        Peter Zijlstra <peterz@...radead.org>, will <will@...nel.org>,
        "boqun.feng" <boqun.feng@...il.com>, npiggin <npiggin@...il.com>,
        dhowells <dhowells@...hat.com>,
        "j.alglave" <j.alglave@....ac.uk>,
        "luc.maranget" <luc.maranget@...ia.fr>, akiyks <akiyks@...il.com>,
        dlustig <dlustig@...dia.com>, joel <joel@...lfernandes.org>,
        urezki <urezki@...il.com>,
        quic_neeraju <quic_neeraju@...cinc.com>,
        frederic <frederic@...nel.org>,
        Kernel development list <linux-kernel@...r.kernel.org>
Subject: Re: [Patch 1/2] tools/memory-model: Update some warning labels



On 1/25/2023 9:20 PM, Alan Stern wrote:
> Some of the warning labels used in the LKMM are unfortunately
> ambiguous.  In particular, the same warning is used for both an
> unmatched rcu_read_lock() call and for an unmatched rcu_read_unlock()
> call.  Likewise for the srcu_* equivalents.  Also, the warning about
> passing a wrong value to srcu_read_unlock() -- i.e., a value different
> from the one returned by the matching srcu_read_lock() -- talks about
> bad nesting rather than non-matching values.
>
> Let's update the warning labels to make their meanings more clear.
>
> Signed-off-by: Alan Stern <stern@...land.harvard.edu>

Reviewed-by: Jonas Oberhauser <jonas.oberhauser@...weicloud.com>

>
> ---
>
>   tools/memory-model/linux-kernel.bell |   10 +++++-----
>   1 file changed, 5 insertions(+), 5 deletions(-)
>
> Index: usb-devel/tools/memory-model/linux-kernel.bell
> ===================================================================
> --- usb-devel.orig/tools/memory-model/linux-kernel.bell
> +++ usb-devel/tools/memory-model/linux-kernel.bell
> @@ -53,8 +53,8 @@ let rcu-rscs = let rec
>   	in matched
>   
>   (* Validate nesting *)
> -flag ~empty Rcu-lock \ domain(rcu-rscs) as unbalanced-rcu-locking
> -flag ~empty Rcu-unlock \ range(rcu-rscs) as unbalanced-rcu-locking
> +flag ~empty Rcu-lock \ domain(rcu-rscs) as unmatched-rcu-lock
> +flag ~empty Rcu-unlock \ range(rcu-rscs) as unmatched-rcu-unlock
>   
>   (* Compute matching pairs of nested Srcu-lock and Srcu-unlock *)
>   let srcu-rscs = let rec
> @@ -69,14 +69,14 @@ let srcu-rscs = let rec
>   	in matched
>   
>   (* Validate nesting *)
> -flag ~empty Srcu-lock \ domain(srcu-rscs) as unbalanced-srcu-locking
> -flag ~empty Srcu-unlock \ range(srcu-rscs) as unbalanced-srcu-locking
> +flag ~empty Srcu-lock \ domain(srcu-rscs) as unmatched-srcu-lock
> +flag ~empty Srcu-unlock \ range(srcu-rscs) as unmatched-srcu-unlock
>   
>   (* Check for use of synchronize_srcu() inside an RCU critical section *)
>   flag ~empty rcu-rscs & (po ; [Sync-srcu] ; po) as invalid-sleep
>   
>   (* Validate SRCU dynamic match *)
> -flag ~empty different-values(srcu-rscs) as srcu-bad-nesting
> +flag ~empty different-values(srcu-rscs) as srcu-bad-value-match
>   
>   (* Compute marked and plain memory accesses *)
>   let Marked = (~M) | IW | Once | Release | Acquire | domain(rmw) | range(rmw) |