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Tue, 10 Mar 2026 09:57:41 -0700 (PDT) Received: from crwood-thinkpadp16vgen1.minnmso.csb ([2601:447:cc81:56d0:ab94:b2cb:29a6:7ac0]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8cd6f56da77sm974761085a.44.2026.03.10.09.57.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Mar 2026 09:57:40 -0700 (PDT) Message-ID: Subject: Re: [PATCH 2/2] cyclictest: simplify rstat_setup From: Crystal Wood To: John Kacur Cc: Lukas Beckmann , John Kacur , rt-users Date: Tue, 10 Mar 2026 11:57:39 -0500 In-Reply-To: <85147e31-053f-1b0f-e200-5d49c1b8b123@gmail.com> References: <20260301212407.3146506-1-lbckmnn@mailbox.org> <20260301212407.3146506-3-lbckmnn@mailbox.org> <9ff2d632fbbc58fda5509a26f0dee26d6c3aefcd.camel@redhat.com> <85147e31-053f-1b0f-e200-5d49c1b8b123@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2 (3.56.2-2.fc42) Precedence: bulk X-Mailing-List: linux-rt-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Tue, 2026-03-10 at 12:18 -0400, John Kacur wrote: >=20 > On Tue, 10 Mar 2026, Crystal Wood wrote: >=20 > > On Mon, 2026-03-09 at 18:55 -0400, John Kacur wrote: > > >=20 > > > On Sun, 1 Mar 2026, Lukas Beckmann wrote: > > > > +static void rstat_setup(void) > > > > +{ > > > > + int fd; > > > > + pid_t pid; > > > > =20 > > > > - if (mptr =3D=3D (void*)-1) > > > > - fprintf(stderr, "ERROR: mmap, %s\n", strerror(errno)); > > > > + pid =3D getpid(); > > > > =20 > > > > - return mptr; > > > > -} > > > > + snprintf(shm_name, SHM_BUF_SIZE, "%s%d", "/cyclictest", pid); > > > > =20 > > > > -static int rstat_mlock(void *mptr) > > > > -{ > > > > - int err; > > >=20 > > > errno =3D 0 before the call to shm_unlink for good defensive programm= ing > > > other than that the patch looks good, I will do a little more testing > >=20 > > Defensive against the library returning -1 without setting errno? Seem= s > > a bit paranoid and cluttery... all for the payoff of an "ERROR: > > shm_unlink Success" message if it ever does happen *and* the old errno > > happened to be ENOENT. > >=20 > > And the current code uses it even in places that print the message > > regardless. > >=20 > > -Crystal > >=20 > >=20 >=20 > Isn't that what defensive programming is? Guarding against something that= =20 > is unlikely? It's one line of code that I requested in a patch that gets= =20 > rid of many lines of code, is that really worth arguing over? Eh, it wasn't so much an argument over this patch, as a "we're supposed to do *what* before each library call?" reflex. -Crystal