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Thu, 16 Jan 2020 17:58:27 +0000 (UTC) Message-Id: <7ac2f0d21652f95e2bbdfa6bd514ae6c7caf53ab.1579196675.git.christophe.leroy@c-s.fr> In-Reply-To: References: From: Christophe Leroy Subject: [RFC PATCH v4 03/11] lib: vdso: only read hrtimer_res when needed in __cvdso_clock_getres() To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , nathanl@linux.ibm.com, arnd@arndb.de, tglx@linutronix.de, vincenzo.frascino@arm.com, luto@kernel.org Date: Thu, 16 Jan 2020 17:58:27 +0000 (UTC) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200116_095831_811916_ABAED408 X-CRM114-Status: GOOD ( 11.17 ) X-Spam-Score: -0.2 (/) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (-0.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [93.17.236.30 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: x86@kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Only perform READ_ONCE(vd[CS_HRES_COARSE].hrtimer_res) for HRES and RAW clocks. Signed-off-by: Christophe Leroy --- lib/vdso/gettimeofday.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c index 9563be3cb5fa..8b3084d9a3ec 100644 --- a/lib/vdso/gettimeofday.c +++ b/lib/vdso/gettimeofday.c @@ -326,7 +326,6 @@ static __maybe_unused int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res) { const struct vdso_data *vd = __arch_get_vdso_data(); - u64 hrtimer_res; u32 msk; u64 ns; @@ -338,7 +337,6 @@ int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res) vd->clock_mode == VDSO_CLOCKMODE_TIMENS) vd = __arch_get_timens_vdso_data(); - hrtimer_res = READ_ONCE(vd[CS_HRES_COARSE].hrtimer_res); /* * Convert the clockid to a bitmask and use it to check which * clocks are handled in the VDSO directly. @@ -348,7 +346,7 @@ int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res) /* * Preserves the behaviour of posix_get_hrtimer_res(). */ - ns = hrtimer_res; + ns = READ_ONCE(vd[CS_HRES_COARSE].hrtimer_res); } else if (msk & VDSO_COARSE) { /* * Preserves the behaviour of posix_get_coarse_res().