summaryrefslogtreecommitdiffstats
path: root/include/vdso/helpers.h
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2026-08-19 10:09:22 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2026-08-19 10:09:22 -0700
commitf4cdf7ca9a1fdcca413157df19753f388a5a224e (patch)
tree60a31895b2446cd7fa27514e8c2843534a0de0da /include/vdso/helpers.h
downloadlinux-stable-f4cdf7ca9a1fdcca413157df19753f388a5a224e.tar.gz
linux-stable-f4cdf7ca9a1fdcca413157df19753f388a5a224e.zip
Merge tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-mediagrafted
Pull media updates from Mauro Carvalho Chehab: - v4l2-core: added ISP statistics support and per-block validation - v4l2-core: Allow unknown HDR10 white point and luminance - New camera sensors: Sony IMX678 and IMX471m, Himax HM1092 IR sensor - New codec: Milos: VPU v2.0 codec support - isp driver: gained support for Dreamchip RPPX1 ISP framework - vsp1 driver: gained support for RZ/T2H and RZ/N2H - Novalake driver: gained CVS support for new NVL hardware - dvb-core: fix feed leak on failed DMX_ADD_PID - several driver fixes, cleanups and minor improvements * tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (308 commits) media: ipu-bridge: check all DMI entries when overriding sensor rotation media: v4l2-async: avoid deleting unlinked ASC entry on link error media: rzg2l-cru: Align bytesperline to hardware DMA stride requirement media: intel/ipu6: fix async notifier cleanup leak on parse error media: staging/ipu7: fix async notifier UAF on probe error path media: amd: isp4: fix self-deadlock in isp4sd_pwron_and_init() error path media: amd: isp4: release partial allocations in isp4if_alloc_fw_gpumem() media: rcar-isp: Fix VSPX reference leaks media: rcar-isp: Release ISPCORE resources media: i2c: imx415: Release runtime PM reference on VBLANK error media: i2c: imx415: Return test pattern write errors media: renesas: vsp1: Declare index variables in for loop statement media: renesas: vsp1: Make reset control optional to support platforms without a reset line media: dt-bindings: media: renesas,vsp1: Document RZ/T2H and RZ/N2H SoCs media: dt-bindings: media: renesas,fcp: Document RZ/T2H and RZ/N2H SoCs media: nxp: imx8-isi: Add additional 32-bit RGB format support media: nxp: imx8-isi: Add 16-bit raw Bayer format support media: nxp: imx8-isi: Implement per-stream reference counting for multiplexed streams media: nxp: imx8-isi: Use BIT_ULL() for 64-bit stream masks media: nxp: imx8-isi: Correct color map between V4L2 and ISI ...
Diffstat (limited to 'include/vdso/helpers.h')
-rw-r--r--include/vdso/helpers.h116
1 files changed, 116 insertions, 0 deletions
diff --git a/include/vdso/helpers.h b/include/vdso/helpers.h
new file mode 100644
index 000000000..65151b681
--- /dev/null
+++ b/include/vdso/helpers.h
@@ -0,0 +1,116 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __VDSO_HELPERS_H
+#define __VDSO_HELPERS_H
+
+#ifndef __ASSEMBLER__
+
+#include <asm/barrier.h>
+#include <vdso/datapage.h>
+#include <vdso/processor.h>
+#include <vdso/clocksource.h>
+
+static __always_inline bool vdso_is_timens_clock(const struct vdso_clock *vc)
+{
+ return IS_ENABLED(CONFIG_TIME_NS) && vc->clock_mode == VDSO_CLOCKMODE_TIMENS;
+}
+
+static __always_inline u32 vdso_read_begin(const struct vdso_clock *vc)
+{
+ u32 seq;
+
+ while (unlikely((seq = READ_ONCE(vc->seq)) & 1))
+ cpu_relax();
+
+ smp_rmb();
+ return seq;
+}
+
+/*
+ * Variant of vdso_read_begin() to handle VDSO_CLOCKMODE_TIMENS.
+ *
+ * Time namespace enabled tasks have a special VVAR page installed which has
+ * vc->seq set to 1 and vc->clock_mode set to VDSO_CLOCKMODE_TIMENS. For non
+ * time namespace affected tasks this does not affect performance because if
+ * vc->seq is odd, i.e. a concurrent update is in progress the extra check for
+ * vc->clock_mode is just a few extra instructions while spin waiting for
+ * vc->seq to become even again.
+ */
+static __always_inline bool vdso_read_begin_timens(const struct vdso_clock *vc, u32 *seq)
+{
+ while (unlikely((*seq = READ_ONCE(vc->seq)) & 1)) {
+ if (vdso_is_timens_clock(vc))
+ return true;
+ cpu_relax();
+ }
+ smp_rmb();
+
+ return false;
+}
+
+static __always_inline u32 vdso_read_retry(const struct vdso_clock *vc,
+ u32 start)
+{
+ u32 seq;
+
+ smp_rmb();
+ seq = READ_ONCE(vc->seq);
+ return unlikely(seq != start);
+}
+
+static __always_inline void vdso_write_seq_begin(struct vdso_clock *vc)
+{
+ /*
+ * WRITE_ONCE() is required otherwise the compiler can validly tear
+ * updates to vc->seq and it is possible that the value seen by the
+ * reader is inconsistent.
+ */
+ WRITE_ONCE(vc->seq, vc->seq + 1);
+}
+
+static __always_inline void vdso_write_seq_end(struct vdso_clock *vc)
+{
+ /*
+ * WRITE_ONCE() is required otherwise the compiler can validly tear
+ * updates to vc->seq and it is possible that the value seen by the
+ * reader is inconsistent.
+ */
+ WRITE_ONCE(vc->seq, vc->seq + 1);
+}
+
+static __always_inline void vdso_write_begin_clock(struct vdso_clock *vc)
+{
+ vdso_write_seq_begin(vc);
+ /* Ensure the sequence invalidation is visible before data is modified */
+ smp_wmb();
+}
+
+static __always_inline void vdso_write_end_clock(struct vdso_clock *vc)
+{
+ /* Ensure the data update is visible before the sequence is set valid again */
+ smp_wmb();
+ vdso_write_seq_end(vc);
+}
+
+static __always_inline void vdso_write_begin(struct vdso_time_data *vd)
+{
+ struct vdso_clock *vc = vd->clock_data;
+
+ vdso_write_seq_begin(&vc[CS_HRES_COARSE]);
+ vdso_write_seq_begin(&vc[CS_RAW]);
+ /* Ensure the sequence invalidation is visible before data is modified */
+ smp_wmb();
+}
+
+static __always_inline void vdso_write_end(struct vdso_time_data *vd)
+{
+ struct vdso_clock *vc = vd->clock_data;
+
+ /* Ensure the data update is visible before the sequence is set valid again */
+ smp_wmb();
+ vdso_write_seq_end(&vc[CS_HRES_COARSE]);
+ vdso_write_seq_end(&vc[CS_RAW]);
+}
+
+#endif /* !__ASSEMBLER__ */
+
+#endif /* __VDSO_HELPERS_H */