File locking refactored (#631)

Remove FileMutex and wire locking into driver subsystems.

TactilityKernel/source/drivers/spi_controller.cpp

@@ -22,6 +22,22 @@ error_t spi_controller_unlock(Device* device) {
     return SPI_DRIVER_API(driver)->unlock(device);
 }
 
+error_t spi_controller_lock_bus_of(Device* device) {
+    Device* parent = device_get_parent(device);
+    if (parent == nullptr || device_get_type(parent) != &SPI_CONTROLLER_TYPE) {
+        return ERROR_NONE;
+    }
+    return spi_controller_lock(parent);
+}
+
+void spi_controller_unlock_bus_of(Device* device) {
+    Device* parent = device_get_parent(device);
+    if (parent == nullptr || device_get_type(parent) != &SPI_CONTROLLER_TYPE) {
+        return;
+    }
+    spi_controller_unlock(parent);
+}
+
 const DeviceType SPI_CONTROLLER_TYPE {
     .name = "spi-controller"
 };

TactilityKernel/source/filesystem/file_mutex.cpp

@@ -1,123 +0,0 @@
-// SPDX-License-Identifier: Apache-2.0
-#include <tactility/filesystem/file_mutex.h>
-#include <tactility/concurrent/mutex.h>
-
-#include <algorithm>
-#include <cstring>
-#include <string>
-#include <vector>
-
-static const FileMutex no_mutex = {
-    .lock = nullptr,
-    .try_lock = nullptr,
-    .unlock = nullptr,
-};
-
-struct FileMutexEntry {
-    FileMutexId id;
-    std::string path;
-    FileMutex mutex;
-};
-
-// Guards mutex_entries against concurrent add/get/remove; unrelated to whether a FileMutex's own
-// lock/unlock is currently held (file_mutex_get() hands out a copy that stays valid regardless of
-// later registry changes - see file_mutex_remove()).
-struct FileMutexLedger {
-    std::vector<FileMutexEntry> entries;
-    FileMutexId next_id = 1;
-    Mutex mutex {};
-
-    FileMutexLedger() { mutex_construct(&mutex); }
-    ~FileMutexLedger() { mutex_destruct(&mutex); }
-
-    void lock() { mutex_lock(&mutex); }
-    void unlock() { mutex_unlock(&mutex); }
-};
-
-static FileMutexLedger& get_ledger() {
-    static FileMutexLedger ledger;
-    return ledger;
-}
-
-extern "C" {
-
-FileMutexId file_mutex_add(const FileMutex* mutex, const char* path) {
-    auto& ledger = get_ledger();
-    ledger.lock();
-
-    for (auto& entry : ledger.entries) {
-        if (entry.path == path) {
-            FileMutexId existing_id = entry.id;
-            ledger.unlock();
-            return existing_id;
-        }
-    }
-
-    FileMutexId new_id = ledger.next_id++;
-    ledger.entries.push_back({
-        .id = new_id,
-        .path = path,
-        .mutex = *mutex
-    });
-
-    ledger.unlock();
-    return new_id;
-}
-
-void file_mutex_remove(FileMutexId id) {
-    auto& ledger = get_ledger();
-    ledger.lock();
-
-    const auto iterator = std::ranges::find_if(ledger.entries, [id](const FileMutexEntry& entry) {
-        return entry.id == id;
-    });
-    if (iterator != ledger.entries.end()) {
-        // Plain erase, not swap-and-pop: file_mutex_get() matches first-registered-wins, so
-        // removal must preserve the relative order of the remaining entries.
-        ledger.entries.erase(iterator);
-    }
-
-    ledger.unlock();
-}
-
-void file_mutex_get(FileMutex* mutex, const char* path) {
-    auto& ledger = get_ledger();
-    std::string path_string = path;
-
-    ledger.lock();
-    for (auto& entry : ledger.entries) {
-        // Match the mount path itself, or a descendant (e.g. "/sdcard" registered, "/sdcard/config.json" requested).
-        bool is_match = path_string == entry.path ||
-            (entry.path == "/" && !path_string.empty() && path_string[0] == '/') ||
-            (path_string.rfind(entry.path, 0) == 0 && path_string[entry.path.size()] == '/');
-        if (is_match) {
-            memcpy(mutex, &entry.mutex, sizeof(FileMutex));
-            ledger.unlock();
-            return;
-        }
-    }
-    ledger.unlock();
-
-    *mutex = no_mutex;
-}
-
-void file_mutex_lock(const FileMutex* mutex) {
-    if (mutex->lock) {
-        mutex->lock();
-    }
-}
-
-bool file_mutex_try_lock(const FileMutex* mutex, TickType_t timeout) {
-    if (mutex->try_lock) {
-        return mutex->try_lock(timeout);
-    }
-    return true;
-}
-
-void file_mutex_unlock(const FileMutex* mutex) {
-    if (mutex->unlock) {
-        mutex->unlock();
-    }
-}
-
-}

TactilityKernel/source/properties_file.cpp

@@ -1,6 +1,5 @@
 // SPDX-License-Identifier: Apache-2.0
 #include <tactility/properties_file.h>
-#include <tactility/filesystem/file_mutex.h>
 #include <tactility/log.h>
 
 #include <cerrno>
@@ -53,14 +52,9 @@ namespace {
 // (fgetc()'s EOF return doesn't by itself distinguish clean end-of-file from a read error -
 // ferror() after the loop does); true otherwise, including for a missing file (ENOENT).
 bool load_from_file(PropertiesFile* file) {
-    FileMutex mutex {};
-    file_mutex_get(&mutex, file->path.c_str());
-    file_mutex_lock(&mutex);
-
     FILE* handle = std::fopen(file->path.c_str(), "r");
     if (handle == nullptr) {
         const int open_error = errno;
-        file_mutex_unlock(&mutex);
         if (open_error == ENOENT) {
             return true;
         }
@@ -105,7 +99,6 @@ bool load_from_file(PropertiesFile* file) {
 
     bool read_ok = std::ferror(handle) == 0;
     std::fclose(handle);
-    file_mutex_unlock(&mutex);
 
     if (!read_ok) {
         LOG_E(TAG, "Failed to read %s", file->path.c_str());
@@ -121,16 +114,11 @@ bool load_from_file(PropertiesFile* file) {
 // @return true if the backing file was fully replaced with the current entries; false (leaving
 // the previous on-disk content untouched) if any step failed.
 bool save_to_file(const PropertiesFile* file) {
-    FileMutex mutex {};
-    file_mutex_get(&mutex, file->path.c_str());
-    file_mutex_lock(&mutex);
-
     std::string temp_path = file->path + ".tmp";
 
     FILE* handle = std::fopen(temp_path.c_str(), "w");
     if (handle == nullptr) {
         LOG_E(TAG, "Failed to open %s", temp_path.c_str());
-        file_mutex_unlock(&mutex);
         return false;
     }
 
@@ -146,7 +134,6 @@ bool save_to_file(const PropertiesFile* file) {
     if (!write_ok || !flush_ok || !close_ok) {
         LOG_E(TAG, "Failed to write %s", temp_path.c_str());
         std::remove(temp_path.c_str());
-        file_mutex_unlock(&mutex);
         return false;
     }
 
@@ -157,11 +144,9 @@ bool save_to_file(const PropertiesFile* file) {
     if (std::rename(temp_path.c_str(), file->path.c_str()) != 0) {
         LOG_E(TAG, "Failed to replace %s", file->path.c_str());
         std::remove(temp_path.c_str());
-        file_mutex_unlock(&mutex);
         return false;
     }
 
-    file_mutex_unlock(&mutex);
     return true;
 }
 

TactilityKernel/source/symbols.c

@@ -44,7 +44,6 @@
 #include <tactility/drivers/usb_msc_device.h>
 #include <tactility/drivers/wifi.h>
 #include <tactility/error.h>
-#include <tactility/filesystem/file_mutex.h>
 #include <tactility/filesystem/file_system.h>
 #include <tactility/memory.h>
 #include <tactility/module.h>
@@ -170,13 +169,6 @@ const struct ModuleSymbol KERNEL_SYMBOLS[] = {
     DEFINE_MODULE_SYMBOL(display_get_frame_buffer_count),
     DEFINE_MODULE_SYMBOL(display_get_backlight),
     DEFINE_MODULE_SYMBOL(DISPLAY_TYPE),
-    // file_mutex
-    DEFINE_MODULE_SYMBOL(file_mutex_add),
-    DEFINE_MODULE_SYMBOL(file_mutex_remove),
-    DEFINE_MODULE_SYMBOL(file_mutex_get),
-    DEFINE_MODULE_SYMBOL(file_mutex_lock),
-    DEFINE_MODULE_SYMBOL(file_mutex_try_lock),
-    DEFINE_MODULE_SYMBOL(file_mutex_unlock),
     // file system
     DEFINE_MODULE_SYMBOL(file_system_mount),
     DEFINE_MODULE_SYMBOL(file_system_unmount),
@@ -306,6 +298,8 @@ const struct ModuleSymbol KERNEL_SYMBOLS[] = {
     DEFINE_MODULE_SYMBOL(spi_controller_lock),
     DEFINE_MODULE_SYMBOL(spi_controller_try_lock),
     DEFINE_MODULE_SYMBOL(spi_controller_unlock),
+    DEFINE_MODULE_SYMBOL(spi_controller_lock_bus_of),
+    DEFINE_MODULE_SYMBOL(spi_controller_unlock_bus_of),
     DEFINE_MODULE_SYMBOL(SPI_CONTROLLER_TYPE),
     // drivers/trackball
     DEFINE_MODULE_SYMBOL(trackball_read_delta),