vasilito
b9874d0941
Add redbear-usb-storage-check in-guest binary that validates USB mass storage read and write I/O: discovers /scheme/disk/ devices, writes a test pattern to sector 2048, reads it back, verifies match, restores original content. Updates test-usb-storage-qemu.sh with write-proof verification step. Includes all accumulated Red Bear OS work: kernel patches, relibc patches, driver infrastructure, DRM/GPU, KDE recipes, firmware, validation tooling, build system hardening, and documentation.
88 lines
3.7 KiB
Diff
88 lines
3.7 KiB
Diff
Fix ENOTRECOVERABLE returned for non-robust mutexes and register main
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thread in OS_TID_TO_PTHREAD.
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The robust mutex liveness check (mutex_owner_id_is_live) was returning
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ENOTRECOVERABLE for non-robust mutexes when the owner appeared dead.
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Per POSIX, the behaviour of a non-robust mutex whose owner has died is
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undefined; returning an error crashes every Rust std::sync::Mutex user.
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For lock_inner, fall through to spin/futex-wait instead. For try_lock,
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return EBUSY instead.
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Additionally, pthread::init() never registered the main thread in
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OS_TID_TO_PTHREAD, so any mutex owned by the main thread would always
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appear to have a dead owner, making the liveness check unreliable.
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diff --git a/src/pthread/mod.rs b/src/pthread/mod.rs
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index 8243a48..c455a67 100644
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--- a/src/pthread/mod.rs
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+++ b/src/pthread/mod.rs
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@@ -43,9 +43,13 @@ pub unsafe fn init() {
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thread.stack_size = STACK_SIZE;
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}
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- unsafe { Tcb::current() }
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- .expect_notls("no TCB present for main thread")
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- .pthread = thread;
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+ let tcb = unsafe { Tcb::current() }
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+ .expect_notls("no TCB present for main thread");
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+ tcb.pthread = thread;
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+
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+ OS_TID_TO_PTHREAD
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+ .lock()
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+ .insert(Sys::current_os_tid(), ForceSendSync(tcb as *const Tcb as *mut Tcb));
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}
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//static NEXT_INDEX: AtomicU32 = AtomicU32::new(FIRST_THREAD_IDX + 1);
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diff --git a/src/sync/pthread_mutex.rs b/src/sync/pthread_mutex.rs
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index af0c429..1b2b3ca 100644
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--- a/src/sync/pthread_mutex.rs
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+++ b/src/sync/pthread_mutex.rs
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@@ -136,14 +136,17 @@ impl RlctMutex {
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Err(thread) => {
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let owner = thread & INDEX_MASK;
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- if !crate::pthread::mutex_owner_id_is_live(owner) {
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- if !self.robust {
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- return Err(Errno(ENOTRECOVERABLE));
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- }
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-
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+ if !crate::pthread::mutex_owner_id_is_live(owner) && self.robust {
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let new_value = (thread & WAITING_BIT) | FUTEX_OWNER_DIED | this_thread;
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match self.inner.compare_exchange(
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thread,
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@@ -152,6 +155,12 @@ impl RlctMutex {
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Ok(_) => return self.finish_lock_acquire(true),
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Err(_) => continue,
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}
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+ } else if !crate::pthread::mutex_owner_id_is_live(owner) {
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+ // Non-robust mutex with apparently-dead owner: per POSIX the
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+ // behaviour is undefined. We conservatively keep spinning /
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+ // futex-waiting rather than returning ENOTRECOVERABLE, which
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+ // would crash any Rust std::sync::Mutex user.
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}
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if spins_left > 0 {
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@@ -241,14 +250,17 @@ impl RlctMutex {
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if current & FUTEX_OWNER_DIED != 0 || (owner != 0 && !crate::pthread::mutex_owner_id_is_live(owner)) {
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- if !self.robust {
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- return Err(Errno(ENOTRECOVERABLE));
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- }
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-
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+ if self.robust {
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let new_value = (current & WAITING_BIT) | FUTEX_OWNER_DIED | this_thread;
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match self.inner.compare_exchange(
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current,
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@@ -257,6 +269,11 @@ impl RlctMutex {
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Ok(_) => return self.finish_lock_acquire(true),
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Err(_) => continue,
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}
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+ } else {
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+ // Non-robust mutex: owner appears dead but POSIX behaviour is
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+ // undefined; report busy rather than ENOTRECOVERABLE.
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+ return Err(Errno(EBUSY));
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+ }
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}
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return Err(Errno(EBUSY));
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