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[34.82.69.139]) by smtp.gmail.com with ESMTPSA id h17-20020aa79f51000000b006e71aec34a8sm5336676pfr.167.2024.04.20.16.49.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 20 Apr 2024 16:49:08 -0700 (PDT) Date: Sat, 20 Apr 2024 23:49:04 +0000 From: Carlos Llamas To: Alice Ryhl Cc: arve@android.com, brauner@kernel.org, gregkh@linuxfoundation.org, joel@joelfernandes.org, kernel-team@android.com, linux-kernel@vger.kernel.org, maco@android.com, surenb@google.com, tkjos@android.com Subject: Re: [PATCH 2/4] binder: migrate ioctl to new PF_SPAM_DETECTION Message-ID: References: <20240417191418.1341988-3-cmllamas@google.com> <20240418081222.3871629-1-aliceryhl@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240418081222.3871629-1-aliceryhl@google.com> On Thu, Apr 18, 2024 at 08:12:22AM +0000, Alice Ryhl wrote: > Carlos Llamas writes: > > @@ -5553,7 +5553,8 @@ static long binder_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) > > goto err; > > } > > binder_inner_proc_lock(proc); > > - proc->oneway_spam_detection_enabled = (bool)enable; > > + proc->flags &= ~PF_SPAM_DETECTION; > > + proc->flags |= enable & PF_SPAM_DETECTION; > > The bitwise and in `enable & PF_SPAM_DETECTION` only works because > PF_SPAM_DETECTION happens to be equal to 1. This seems pretty fragile to > me. Would you be willing to do this instead? > > proc->flags &= ~PF_SPAM_DETECTION; > if (enable) > proc->flags |= PF_SPAM_DETECTION; > I don't think it is fragile since PF_SPAM_DETECTION is fixed. However, I agree the code is missing context about the flag being bit 0 and your version addresses this problem. So I'll take it for v2, thanks! > > Carlos Llamas writes: > > - if (proc->oneway_spam_detection_enabled && > > - w->type == BINDER_WORK_TRANSACTION_ONEWAY_SPAM_SUSPECT) > > + if (proc->flags & PF_SPAM_DETECTION && > > + w->type == BINDER_WORK_TRANSACTION_ONEWAY_SPAM_SUSPECT) > > Maybe I am just not sufficiently familiar with C, but I had to look up > the operator precedence rules for this one. Could we add parenthesises > around `proc->flags & PF_SPAM_DETECTION`? Or even define a macro for it? I think this is fairly common in C but I can definitly add the extra paranthesis if it helps. -- Carlos Llamas