Remove map from fd_map, change to fd_table.

This renames FDMap to FDTable and drops the kernel.FD type, which had an entire
package to itself and didn't serve much use (it was freely cast between types,
and served as more of an annoyance than providing any protection.)

Based on BenchmarkFDLookupAndDecRef-12, we can expect 5-10 ns per lookup
operation, and 10-15 ns per concurrent lookup operation of savings.

This also fixes two tangential usage issues with the FDMap. Namely, non-atomic
use of NewFDFrom and associated calls to Remove (that are both racy and fail to
drop the reference on the underlying file.)

PiperOrigin-RevId: 256285890

1 files changed, 6 insertions, 7 deletions

diff --git a/pkg/sentry/syscalls/linux/sys_timerfd.go b/pkg/sentry/syscalls/linux/sys_timerfd.go
index ea6d44315..1ce5ce4c3 100644
--- a/pkg/sentry/syscalls/linux/sys_timerfd.go
+++ b/pkg/sentry/syscalls/linux/sys_timerfd.go
@@ -20,7 +20,6 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/fs"
 	"gvisor.dev/gvisor/pkg/sentry/fs/timerfd"
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
-	"gvisor.dev/gvisor/pkg/sentry/kernel/kdefs"
 	ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
 	"gvisor.dev/gvisor/pkg/syserror"
 )
@@ -49,9 +48,9 @@ func TimerfdCreate(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel
 		NonBlocking: flags&linux.TFD_NONBLOCK != 0,
 	})
 
-	fd, err := t.FDMap().NewFDFrom(0, f, kernel.FDFlags{
+	fd, err := t.NewFDFrom(0, f, kernel.FDFlags{
 		CloseOnExec: flags&linux.TFD_CLOEXEC != 0,
-	}, t.ThreadGroup().Limits())
+	})
 	if err != nil {
 		return 0, nil, err
 	}
@@ -61,7 +60,7 @@ func TimerfdCreate(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel
 
 // TimerfdSettime implements Linux syscall timerfd_settime(2).
 func TimerfdSettime(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
-	fd := kdefs.FD(args[0].Int())
+	fd := args[0].Int()
 	flags := args[1].Int()
 	newValAddr := args[2].Pointer()
 	oldValAddr := args[3].Pointer()
@@ -70,7 +69,7 @@ func TimerfdSettime(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kerne
 		return 0, nil, syserror.EINVAL
 	}
 
-	f := t.FDMap().GetFile(fd)
+	f := t.GetFile(fd)
 	if f == nil {
 		return 0, nil, syserror.EBADF
 	}
@@ -101,10 +100,10 @@ func TimerfdSettime(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kerne
 
 // TimerfdGettime implements Linux syscall timerfd_gettime(2).
 func TimerfdGettime(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
-	fd := kdefs.FD(args[0].Int())
+	fd := args[0].Int()
 	curValAddr := args[1].Pointer()
 
-	f := t.FDMap().GetFile(fd)
+	f := t.GetFile(fd)
 	if f == nil {
 		return 0, nil, syserror.EBADF
 	}