Date: Sat, 20 Sep 2025 19:34:28 GMT From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 4c3a868d13c0 - main - fcntl(F_SETFL): only allow one thread to perform F_SETFL Message-ID: <202509201934.58KJYSEN040345@gitrepo.freebsd.org>
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The branch main has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=4c3a868d13c053ef173268cdfe1365978a282178 commit 4c3a868d13c053ef173268cdfe1365978a282178 Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2025-09-11 10:05:04 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2025-09-20 19:24:10 +0000 fcntl(F_SETFL): only allow one thread to perform F_SETFL Use f_vflags file locking for this. Allowing more than one thread handling F_SETFL might cause de-sync between real driver state and flags. Reviewed by: markj Tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 2 weeks Differential revision: https://reviews.freebsd.org/D52487 --- sys/kern/kern_descrip.c | 3 +++ sys/kern/vfs_vnops.c | 36 ++++++++++++++++++++++++++++++++++++ sys/sys/file.h | 4 ++++ 3 files changed, 43 insertions(+) diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c index 2a833d2eafbe..19118eb7f275 100644 --- a/sys/kern/kern_descrip.c +++ b/sys/kern/kern_descrip.c @@ -658,6 +658,7 @@ kern_fcntl(struct thread *td, int fd, int cmd, intptr_t arg) error = EBADF; break; } + fsetfl_lock(fp); do { tmp = flg = fp->f_flag; tmp &= ~FCNTLFLAGS; @@ -677,6 +678,7 @@ kern_fcntl(struct thread *td, int fd, int cmd, intptr_t arg) if (error != 0) goto revert_nonblock; } + fsetfl_unlock(fp); fdrop(fp, td); break; revert_nonblock: @@ -691,6 +693,7 @@ revert_flags: tmp |= got_cleared; tmp &= ~got_set; } while (atomic_cmpset_int(&fp->f_flag, flg, tmp) == 0); + fsetfl_unlock(fp); fdrop(fp, td); break; diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c index f81c2033d95e..3d4567b6ab1e 100644 --- a/sys/kern/vfs_vnops.c +++ b/sys/kern/vfs_vnops.c @@ -896,6 +896,18 @@ foffset_read(struct file *fp) return (atomic_load_long(&fp->f_offset)); } +void +fsetfl_lock(struct file *fp) +{ + file_v_lock(fp, FILE_V_SETFL_LOCKED, FILE_V_SETFL_LOCK_WAITING); +} + +void +fsetfl_unlock(struct file *fp) +{ + file_v_unlock(fp, FILE_V_SETFL_LOCKED, FILE_V_SETFL_LOCK_WAITING); +} + #else /* OFF_MAX <= LONG_MAX */ static void @@ -971,6 +983,30 @@ foffset_read(struct file *fp) return (foffset_lock(fp, FOF_NOLOCK)); } + +void +fsetfl_lock(struct file *fp) +{ + struct mtx *mtxp; + + mtxp = mtx_pool_find(mtxpool_sleep, fp); + mtx_lock(mtxp); + file_v_lock_mtxp(fp, mtxp, FILE_V_SETFL_LOCKED, + FILE_V_SETFL_LOCK_WAITING); + mtx_unlock(mtxp); +} + +void +fsetfl_unlock(struct file *fp) +{ + struct mtx *mtxp; + + mtxp = mtx_pool_find(mtxpool_sleep, fp); + mtx_lock(mtxp); + file_v_unlock_mtxp(fp, mtxp, FILE_V_SETFL_LOCKED, + FILE_V_SETFL_LOCK_WAITING); + mtx_unlock(mtxp); +} #endif void diff --git a/sys/sys/file.h b/sys/sys/file.h index 9a072121e25f..c44fd0f28929 100644 --- a/sys/sys/file.h +++ b/sys/sys/file.h @@ -93,6 +93,8 @@ void foffset_lock_pair(struct file *fp1, off_t *off1p, struct file *fp2, void foffset_lock_uio(struct file *fp, struct uio *uio, int flags); void foffset_unlock(struct file *fp, off_t val, int flags); void foffset_unlock_uio(struct file *fp, struct uio *uio, int flags); +void fsetfl_lock(struct file *fp); +void fsetfl_unlock(struct file *fp); static inline off_t foffset_get(struct file *fp) @@ -222,6 +224,8 @@ struct file { #define FILE_V_FOFFSET_LOCKED 0x0001 #define FILE_V_FOFFSET_LOCK_WAITING 0x0002 +#define FILE_V_SETFL_LOCKED 0x0004 +#define FILE_V_SETFL_LOCK_WAITING 0x0008 #endif /* __BSD_VISIBLE */ #endif /* _KERNEL || _WANT_FILE */
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