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(cst-prg-86-144.cust.vodafone.cz. [46.135.86.144]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ac2395174c8sm1081722366b.85.2025.03.12.09.19.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 Mar 2025 09:19:50 -0700 (PDT) From: Mateusz Guzik To: brauner@kernel.org Cc: viro@zeniv.linux.org.uk, jack@suse.cz, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Mateusz Guzik Subject: [PATCH] fs: use debug-only asserts around fd allocation and install Date: Wed, 12 Mar 2025 17:19:41 +0100 Message-ID: <20250312161941.1261615-1-mjguzik@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 This also restores the check which got removed in 52732bb9abc9ee5b ("fs/file.c: remove sanity_check and add likely/unlikely in alloc_fd()") for performance reasons -- they no longer apply with a debug-only variant. Signed-off-by: Mateusz Guzik Reviewed-by: Jan Kara --- I have about 0 opinion whether this should be BUG or WARN, the code was already inconsistent on this front. If you want the latter, I'll have 0 complaints if you just sed it and commit as yours. This reminded me to sort out that litmus test for smp_rmb, hopefully soon(tm) as it is now nagging me. fs/file.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/file.c b/fs/file.c index 6c159ede55f1..09460ec74ef8 100644 --- a/fs/file.c +++ b/fs/file.c @@ -582,6 +582,7 @@ static int alloc_fd(unsigned start, unsigned end, unsigned flags) __set_open_fd(fd, fdt, flags & O_CLOEXEC); error = fd; + VFS_BUG_ON(rcu_access_pointer(fdt->fd[fd]) != NULL); out: spin_unlock(&files->file_lock); @@ -647,7 +648,7 @@ void fd_install(unsigned int fd, struct file *file) rcu_read_unlock_sched(); spin_lock(&files->file_lock); fdt = files_fdtable(files); - WARN_ON(fdt->fd[fd] != NULL); + VFS_BUG_ON(fdt->fd[fd] != NULL); rcu_assign_pointer(fdt->fd[fd], file); spin_unlock(&files->file_lock); return; @@ -655,7 +656,7 @@ void fd_install(unsigned int fd, struct file *file) /* coupled with smp_wmb() in expand_fdtable() */ smp_rmb(); fdt = rcu_dereference_sched(files->fdt); - BUG_ON(fdt->fd[fd] != NULL); + VFS_BUG_ON(fdt->fd[fd] != NULL); rcu_assign_pointer(fdt->fd[fd], file); rcu_read_unlock_sched(); }