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([2001:288:7001:2703:35d0:8dad:cfe4:6cb9]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-225c68a406fsm102788585ad.64.2025.03.18.19.26.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 18 Mar 2025 19:26:48 -0700 (PDT) From: I Hsin Cheng To: rostedt@goodmis.org Cc: paulmck@kernel.org, frederic@kernel.org, neeraj.upadhyay@kernel.org, joel@joelfernandes.org, josh@joshtriplett.org, boqun.feng@gmail.com, urezki@gmail.com, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, qiang.zhang1211@gmail.com, ojeda@kernel.org, alex.gaynor@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, benno.lossin@proton.me, a.hindborg@kernel.org, aliceryhl@google.com, tmgross@umich.edu, dakr@kernel.org, rcu@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, linux-kernel-mentees@lists.linux.dev, jserv@ccns.ncku.edu.tw, I Hsin Cheng Subject: [PATCH v2] rust: sync: rcu: Mark Guard methods as inline Date: Wed, 19 Mar 2025 10:26:40 +0800 Message-ID: <20250319022640.970207-1-richard120310@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Currently the implementation of "Guard" methods are basically wrappers around rcu's function within kernel. Building the kernel with llvm 18.1.8 on x86_64 machine will generate the following symbols: $ nm vmlinux | grep ' _R'.*Guard | rustfilt ffffffff817b6c90 T ::new ffffffff817b6cb0 T ::unlock ffffffff817b6cd0 T ::drop ffffffff817b6c90 T ::de= fault These Rust symbols are basically wrappers around functions "rcu_read_lock" and "rcu_read_unlock". Marking them as inline can reduce the generation of these symbols, and saves the size of code generation for 132 bytes. $ ./scripts/bloat-o-meter vmlinux_old vmlinux_new add/remove: 0/10 grow/shrink: 0/1 up/down: 0/-132 (-132) Function old new delta _RNvXs1_Cs4gouIKNZ4iT_15rust_driver_pciNtB5_12SampleDriverNtNtCsaYBeKL739Xz= _6kernel3pci6Driver5probe 1041 1034 -7 _RNvXs_NtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB4_5GuardNtNtCsdaXADs8PRFB_4core= 7default7Default7default 9 - -9 _RNvXs0_NtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB5_5GuardNtNtNtCsdaXADs8PRFB_4c= ore3ops4drop4Drop4drop 9 - -9 _RNvNtNtCsaYBeKL739Xz_6kernel4sync3rcu9read_lock 9 - -9 _RNvMNtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB2_5Guard6unlock 9 - = -9 _RNvMNtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB2_5Guard3new 9 - = -9 __pfx__RNvXs_NtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB4_5GuardNtNtCsdaXADs8PRFB= _4core7default7Default7default 16 - -16 __pfx__RNvXs0_NtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB5_5GuardNtNtNtCsdaXADs8P= RFB_4core3ops4drop4Drop4drop 16 - -16 __pfx__RNvNtNtCsaYBeKL739Xz_6kernel4sync3rcu9read_lock 16 - = -16 __pfx__RNvMNtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB2_5Guard6unlock 16 = - -16 __pfx__RNvMNtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB2_5Guard3new 16 = - -16 Total: Before=3D23365955, After=3D23365823, chg -0.00% Link: https://github.com/Rust-for-Linux/linux/issues/1145 Signed-off-by: I Hsin Cheng Acked-by: Miguel Ojeda Reviewed-by: Benno Lossin Reviewed-by: Charalampos Mitrodimas Reviewed-by: Joel Fernandes --- Changelog: v1 -> v2: - Mark read_lock() as inline as well - Fix typos --- rust/kernel/sync/rcu.rs | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/rust/kernel/sync/rcu.rs b/rust/kernel/sync/rcu.rs index b51d9150ffe2..a32bef6e490b 100644 --- a/rust/kernel/sync/rcu.rs +++ b/rust/kernel/sync/rcu.rs @@ -17,6 +17,7 @@ =20 impl Guard { /// Acquires the RCU read side lock and returns a guard. + #[inline] pub fn new() -> Self { // SAFETY: An FFI call with no additional requirements. unsafe { bindings::rcu_read_lock() }; @@ -25,16 +26,19 @@ pub fn new() -> Self { } =20 /// Explicitly releases the RCU read side lock. + #[inline] pub fn unlock(self) {} } =20 impl Default for Guard { + #[inline] fn default() -> Self { Self::new() } } =20 impl Drop for Guard { + #[inline] fn drop(&mut self) { // SAFETY: By the type invariants, the RCU read side is locked, so= it is ok to unlock it. unsafe { bindings::rcu_read_unlock() }; @@ -42,6 +46,7 @@ fn drop(&mut self) { } =20 /// Acquires the RCU read side lock. +#[inline] pub fn read_lock() -> Guard { Guard::new() } --=20 2.43.0