[PATCH 05/11] pidfs: Use test_bit_acquire() for attr flag tests
From: Jinjie Ruan <hidden>
Date: 2026-08-25 09:53:55
Also in:
linux-can, linux-ext4, linux-fsdevel, lkml
Subsystem:
filesystems (vfs and infrastructure), the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
Replace test_bit() + smp_rmb() with test_bit_acquire() for PIDFS_ATTR_BIT_EXIT and PIDFS_ATTR_BIT_COREDUMP tests in pidfd_info(). The acquire semantics ensure that if the flag is observed set, the associated attr fields written before smp_wmb() + set_bit() are also visible. Writers keep smp_wmb() + set_bit() since no release bitop exists. Assisted-by: DeepSeek:DeepSeek-V3 Signed-off-by: Jinjie Ruan <redacted> --- fs/pidfs.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/fs/pidfs.c b/fs/pidfs.c
index a6a643f15d08..2cd0fab73180 100644
--- a/fs/pidfs.c
+++ b/fs/pidfs.c@@ -393,8 +393,7 @@ static long pidfd_info(struct file *file, unsigned int cmd, unsigned long arg) attr = READ_ONCE(pid->attr); if (mask & PIDFD_INFO_EXIT) { - if (test_bit(PIDFS_ATTR_BIT_EXIT, &attr->attr_mask)) { - smp_rmb(); + if (test_bit_acquire(PIDFS_ATTR_BIT_EXIT, &attr->attr_mask)) { kinfo.mask |= PIDFD_INFO_EXIT; #ifdef CONFIG_CGROUPS kinfo.cgroupid = attr->cgroupid;
@@ -405,8 +404,7 @@ static long pidfd_info(struct file *file, unsigned int cmd, unsigned long arg) } if (mask & PIDFD_INFO_COREDUMP) { - if (test_bit(PIDFS_ATTR_BIT_COREDUMP, &attr->attr_mask)) { - smp_rmb(); + if (test_bit_acquire(PIDFS_ATTR_BIT_COREDUMP, &attr->attr_mask)) { kinfo.mask |= PIDFD_INFO_COREDUMP | PIDFD_INFO_COREDUMP_SIGNAL | PIDFD_INFO_COREDUMP_CODE; kinfo.coredump_mask = attr->coredump_mask; kinfo.coredump_signal = attr->coredump_signal;
--
2.34.1