diff options
Diffstat (limited to 'src/libstd/rt/thread.rs')
| -rw-r--r-- | src/libstd/rt/thread.rs | 63 |
1 files changed, 26 insertions, 37 deletions
diff --git a/src/libstd/rt/thread.rs b/src/libstd/rt/thread.rs index 7b24c94b518..e27698d7dd0 100644 --- a/src/libstd/rt/thread.rs +++ b/src/libstd/rt/thread.rs @@ -221,7 +221,7 @@ mod imp { PTHREAD_CREATE_JOINABLE), 0); // Reserve room for the red zone, the runtime's stack of last resort. - let stack_size = cmp::max(stack, RED_ZONE + __pthread_get_minstack(&attr) as uint); + let stack_size = cmp::max(stack, RED_ZONE + min_stack_size(&attr) as uint); match pthread_attr_setstacksize(&mut attr, stack_size as libc::size_t) { 0 => { }, @@ -261,51 +261,39 @@ mod imp { #[cfg(not(target_os = "macos"), not(target_os = "android"))] pub unsafe fn yield_now() { assert_eq!(pthread_yield(), 0); } - #[cfg(not(target_os = "linux"))] - unsafe fn __pthread_get_minstack(_: *libc::pthread_attr_t) -> libc::size_t { - libc::PTHREAD_STACK_MIN - } - // glibc >= 2.15 has a __pthread_get_minstack() function that returns // PTHREAD_STACK_MIN plus however many bytes are needed for thread-local // storage. We need that information to avoid blowing up when a small stack // is created in an application with big thread-local storage requirements. // See #6233 for rationale and details. // - // Dynamically resolve the symbol for compatibility with older versions - // of glibc. Assumes that we've been dynamically linked to libpthread - // but that is currently always the case. Note that this means we take - // a dlopen/dlsym/dlclose hit for every new thread. Mitigating that by - // caching the symbol or the function's return value has its drawbacks: - // - // * Caching the symbol breaks when libpthread.so is reloaded because - // its address changes. - // - // * Caching the return value assumes that it's a fixed quantity. - // Not very future-proof and untrue in the presence of guard pages - // The reason __pthread_get_minstack() takes a *libc::pthread_attr_t - // as its argument is because it takes pthread_attr_setguardsize() into - // account. - // - // A better solution is to define __pthread_get_minstack() as a weak symbol - // but there is currently no way to express that in Rust code. - #[cfg(target_os = "linux")] - unsafe fn __pthread_get_minstack(attr: *libc::pthread_attr_t) -> libc::size_t { - use option::None; - use result::{Err, Ok}; - use unstable::dynamic_lib; - match dynamic_lib::DynamicLibrary::open(None) { - Err(err) => fail!("DynamicLibrary::open(): {}", err), - Ok(handle) => { - match handle.symbol::<extern "C" fn(*libc::pthread_attr_t) -> - libc::size_t>("__pthread_get_minstack") { - Err(_) => libc::PTHREAD_STACK_MIN, - Ok(__pthread_get_minstack) => __pthread_get_minstack(attr), - } - } + // Link weakly to the symbol for compatibility with older versions of glibc. + // Assumes that we've been dynamically linked to libpthread but that is + // currently always the case. Note that you need to check that the symbol + // is non-null before calling it! + #[cfg(target_os = "linux", not(stage0))] + fn min_stack_size(attr: *libc::pthread_attr_t) -> libc::size_t { + use ptr::RawPtr; + type F = extern "C" unsafe fn(*libc::pthread_attr_t) -> libc::size_t; + extern { + #[linkage = "extern_weak"] + static __pthread_get_minstack: *(); + } + if __pthread_get_minstack.is_null() { + PTHREAD_STACK_MIN + } else { + unsafe { cast::transmute::<*(), F>(__pthread_get_minstack)(attr) } } } + // __pthread_get_minstack() is marked as weak but extern_weak linkage is + // not supported on OS X, hence this kludge... + #[cfg(not(target_os = "linux"))] + #[cfg(stage0)] + fn min_stack_size(_: *libc::pthread_attr_t) -> libc::size_t { + PTHREAD_STACK_MIN + } + extern { fn pthread_create(native: *mut libc::pthread_t, attr: *libc::pthread_attr_t, @@ -347,3 +335,4 @@ mod tests { assert_eq!(42, Thread::start_stack(1, proc () 42).join()); } } + |