fix(procfs): align seq read semantics, re-parent every thread, resolve /proc/<nr> by tid

kernel/src/filesystem/procfs/cmdline.rs

@@ -9,7 +9,7 @@ use crate::{
     filesystem::{
         procfs::{
             template::{Builder, FileOps, ProcFileBuilder},
-            utils::proc_read,
+            utils::proc_read_snapshot,
         },
         vfs::{FilePrivateData, IndexNode, InodeMode},
     },
@@ -53,10 +53,11 @@ impl FileOps for CmdlineFileOps {
         offset: usize,
         len: usize,
         buf: &mut [u8],
-        _data: MutexGuard<FilePrivateData>,
+        mut data: MutexGuard<FilePrivateData>,
     ) -> Result<usize, SystemError> {
-        let content = Self::generate_cmdline_content();
-
-        proc_read(offset, len, buf, &content)
+        // `single_open()`: one fd sees one kernel command line record.
+        proc_read_snapshot(offset, len, buf, &mut data, || {
+            Ok(Self::generate_cmdline_content())
+        })
     }
 }

kernel/src/filesystem/procfs/cpuinfo.rs

@@ -5,7 +5,7 @@ use crate::{
     filesystem::{
         procfs::{
             template::{Builder, FileOps, ProcFileBuilder},
-            utils::proc_read,
+            utils::proc_read_snapshot,
         },
         vfs::{IndexNode, InodeMode},
     },
@@ -34,22 +34,26 @@ impl FileOps for CpuInfoFileOps {
         offset: usize,
         len: usize,
         buf: &mut [u8],
-        _: crate::libs::mutex::MutexGuard<crate::filesystem::vfs::FilePrivateData>,
+        mut data: crate::libs::mutex::MutexGuard<crate::filesystem::vfs::FilePrivateData>,
     ) -> Result<usize, SystemError> {
-        let mut data: Vec<u8> = vec![];
-        let cpu_manager = smp_cpu_manager();
-
-        // 遍历所有present的CPU
-        for cpu_id in cpu_manager.present_cpus().iter_cpu() {
-            // 生成每个 CPU 的信息
-            let cpu_info = generate_cpu_info(cpu_id);
-            data.extend_from_slice(cpu_info.as_bytes());
-
-            // 在每个CPU信息之间添加空行分隔
-            data.push(b'\n');
-        }
+        // `seq_file` (Linux `seq_open(&cpuinfo_op)`, `fs/proc/cpuinfo.c`): one
+        // fd sees one rendered record.
+        proc_read_snapshot(offset, len, buf, &mut data, || {
+            let mut content: Vec<u8> = vec![];
+            let cpu_manager = smp_cpu_manager();
+
+            // Walk every present CPU.
+            for cpu_id in cpu_manager.present_cpus().iter_cpu() {
+                // Render this CPU's record.
+                let cpu_info = generate_cpu_info(cpu_id);
+                content.extend_from_slice(cpu_info.as_bytes());
+
+                // Blank line between CPU records, as Linux does.
+                content.push(b'\n');
+            }
 
-        proc_read(offset, len, buf, &data)
+            Ok(content)
+        })
     }
 }
 

kernel/src/filesystem/procfs/loadavg.rs

@@ -3,7 +3,7 @@ use crate::{
     filesystem::{
         procfs::{
             template::{Builder, FileOps, ProcFileBuilder},
-            utils::{proc_read, trim_string},
+            utils::{proc_read_snapshot, trim_string},
         },
         vfs::{FilePrivateData, IndexNode, InodeMode},
     },
@@ -71,9 +71,11 @@ impl FileOps for LoadavgFileOps {
         offset: usize,
         len: usize,
         buf: &mut [u8],
-        _data: MutexGuard<FilePrivateData>,
+        mut data: MutexGuard<FilePrivateData>,
     ) -> Result<usize, SystemError> {
-        let content = Self::generate_loadavg_content();
-        proc_read(offset, len, buf, &content)
+        // `single_open()`: one fd sees one load-average record.
+        proc_read_snapshot(offset, len, buf, &mut data, || {
+            Ok(Self::generate_loadavg_content())
+        })
     }
 }

kernel/src/filesystem/procfs/meminfo.rs

@@ -8,7 +8,7 @@ use crate::{
     filesystem::{
         procfs::{
             template::{Builder, FileOps, ProcFileBuilder},
-            utils::{proc_read, trim_string},
+            utils::{proc_read_snapshot, trim_string},
         },
         vfs::{FilePrivateData, IndexNode, InodeMode},
     },
@@ -107,9 +107,11 @@ impl FileOps for MeminfoFileOps {
         offset: usize,
         len: usize,
         buf: &mut [u8],
-        _data: MutexGuard<FilePrivateData>,
+        mut data: MutexGuard<FilePrivateData>,
     ) -> Result<usize, SystemError> {
-        let content = Self::generate_meminfo_content();
-        proc_read(offset, len, buf, &content)
+        // `single_open()`: one fd sees one meminfo record.
+        proc_read_snapshot(offset, len, buf, &mut data, || {
+            Ok(Self::generate_meminfo_content())
+        })
     }
 }

kernel/src/filesystem/procfs/mod.rs

@@ -3,16 +3,20 @@
 //! 实现 Linux 兼容的 /proc 文件系统
 
 use crate::mm::ucontext::AddressSpace;
-use alloc::{sync::Arc, vec::Vec};
+use alloc::sync::Arc;
 use system_error::SystemError;
 
 use crate::{
     libs::once::Once,
-    process::{cred::Cred, namespace::pid_namespace::INIT_PID_NAMESPACE, ProcessManager},
+    process::{
+        cred::Cred, namespace::net_namespace::NetNamespace,
+        namespace::pid_namespace::INIT_PID_NAMESPACE, ProcessManager,
+    },
 };
 
 use super::vfs::mount::MountFlags;
 use super::vfs::InodeMode;
+use mount::MountView;
 
 mod cmdline;
 mod cpuinfo;
@@ -50,17 +54,38 @@ pub(super) use template::Builder;
 /// procfs 文件私有数据
 #[derive(Debug, Clone)]
 pub struct ProcfsFilePrivateData {
-    pub data: Vec<u8>,
     pub open_cred: Arc<Cred>,
-    pub pinned_vm: Option<Arc<AddressSpace>>,
+    /// Address space this fd was opened on, taken by `open()` of the files that
+    /// address one (`/proc/[pid]/mem`, `/proc/[pid]/maps`).
+    ///
+    /// The descriptor, deliberately not the memory: Linux `proc_mem_open()`
+    /// grabs the `mm_struct` and then drops the user reference again
+    /// ("but do not pin its memory"), so an `execve()` or an exit in the target
+    /// still tears the mappings down while this fd stays open. Each read
+    /// re-checks the user count (`mmget_not_zero()`), which is how both files
+    /// learn that there is nothing left to serve.
+    pub(crate) pinned_vm: Option<Arc<AddressSpace>>,
+    /// Streaming state of a seq-style record (Linux `struct seq_file`). Only
+    /// `utils::proc_read_seq()` and `utils::proc_read_snapshot()` touch it.
+    pub(crate) seq: utils::ProcfsSeq,
+    /// Mount namespace and root directory pinned by `open()` for
+    /// `/proc/[pid]/{mounts,mountinfo,mountstats}`, as `mounts_open_common()`
+    /// does; `None` for every other procfs file.
+    pub(crate) mount_view: Option<MountView>,
+    /// Network namespace pinned by `open()` for the files under `/proc/net`,
+    /// as `seq_open_net()` stores it in `seq_net_private`; `None` for every
+    /// other procfs file.
+    pub(crate) net_ns: Option<Arc<NetNamespace>>,
 }
 
 impl ProcfsFilePrivateData {
     pub fn new() -> Self {
         ProcfsFilePrivateData {
-            data: Vec::new(),
             open_cred: ProcessManager::current_pcb().cred(),
             pinned_vm: None,
+            seq: utils::ProcfsSeq::default(),
+            mount_view: None,
+            net_ns: None,
         }
     }
 }