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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 /rust/proc-macro2/detection.rs
downloadlinux-stable-f4cdf7ca9a1fdcca413157df19753f388a5a224e.tar.gz
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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 'rust/proc-macro2/detection.rs')
-rw-r--r--rust/proc-macro2/detection.rs77
1 files changed, 77 insertions, 0 deletions
diff --git a/rust/proc-macro2/detection.rs b/rust/proc-macro2/detection.rs
new file mode 100644
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+++ b/rust/proc-macro2/detection.rs
@@ -0,0 +1,77 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use core::sync::atomic::{AtomicUsize, Ordering};
+use std::sync::Once;
+
+static WORKS: AtomicUsize = AtomicUsize::new(0);
+static INIT: Once = Once::new();
+
+pub(crate) fn inside_proc_macro() -> bool {
+ match WORKS.load(Ordering::Relaxed) {
+ 1 => return false,
+ 2 => return true,
+ _ => {}
+ }
+
+ INIT.call_once(initialize);
+ inside_proc_macro()
+}
+
+pub(crate) fn force_fallback() {
+ WORKS.store(1, Ordering::Relaxed);
+}
+
+pub(crate) fn unforce_fallback() {
+ initialize();
+}
+
+#[cfg(not(no_is_available))]
+fn initialize() {
+ let available = proc_macro::is_available();
+ WORKS.store(available as usize + 1, Ordering::Relaxed);
+}
+
+// Swap in a null panic hook to avoid printing "thread panicked" to stderr,
+// then use catch_unwind to determine whether the compiler's proc_macro is
+// working. When proc-macro2 is used from outside of a procedural macro all
+// of the proc_macro crate's APIs currently panic.
+//
+// The Once is to prevent the possibility of this ordering:
+//
+// thread 1 calls take_hook, gets the user's original hook
+// thread 1 calls set_hook with the null hook
+// thread 2 calls take_hook, thinks null hook is the original hook
+// thread 2 calls set_hook with the null hook
+// thread 1 calls set_hook with the actual original hook
+// thread 2 calls set_hook with what it thinks is the original hook
+//
+// in which the user's hook has been lost.
+//
+// There is still a race condition where a panic in a different thread can
+// happen during the interval that the user's original panic hook is
+// unregistered such that their hook is incorrectly not called. This is
+// sufficiently unlikely and less bad than printing panic messages to stderr
+// on correct use of this crate. Maybe there is a libstd feature request
+// here. For now, if a user needs to guarantee that this failure mode does
+// not occur, they need to call e.g. `proc_macro2::Span::call_site()` from
+// the main thread before launching any other threads.
+#[cfg(no_is_available)]
+fn initialize() {
+ use std::panic::{self, PanicInfo};
+
+ type PanicHook = dyn Fn(&PanicInfo) + Sync + Send + 'static;
+
+ let null_hook: Box<PanicHook> = Box::new(|_panic_info| { /* ignore */ });
+ let sanity_check = &*null_hook as *const PanicHook;
+ let original_hook = panic::take_hook();
+ panic::set_hook(null_hook);
+
+ let works = panic::catch_unwind(proc_macro::Span::call_site).is_ok();
+ WORKS.store(works as usize + 1, Ordering::Relaxed);
+
+ let hopefully_null_hook = panic::take_hook();
+ panic::set_hook(original_hook);
+ if sanity_check != &*hopefully_null_hook {
+ panic!("observed race condition in proc_macro2::inside_proc_macro");
+ }
+}