Cleanup of dead code suggested by Clang Static Analyzer (#14380)
I recently gained the ability to run Clang's static analyzer on the linux kernel modules via a few hacks. This extended coverage to code that was previously missed since Clang's static analyzer only looked at code that we built in userspace. Running it against the Linux kernel modules built from my local branch produced a total of 72 reports against my local branch. Of those, 50 were reports of logic errors and 22 were reports of dead code. Since we already had cleaned up all of the previous dead code reports, I felt it would be a good next step to clean up these dead code reports. Clang did a further breakdown of the dead code reports into: Dead assignment 15 Dead increment 2 Dead nested assignment 5 The benefit of cleaning these up, especially in the case of dead nested assignment, is that they can expose places where our error handling is incorrect. A number of them were fairly straight forward. However several were not: In vdev_disk_physio_completion(), not only were we not using the return value from the static function vdev_disk_dio_put(), but nothing used it, so I changed it to return void and removed the existing (void) cast in the other area where we call it in addition to no longer storing it to a stack value. In FSE_createDTable(), the function is dead code. Its helper function FSE_freeDTable() is also dead code, as are the CPP definitions in `module/zstd/include/zstd_compat_wrapper.h`. We just delete it all. In zfs_zevent_wait(), we have an optimization opportunity. cv_wait_sig() returns 0 if there are waiting signals and 1 if there are none. The Linux SPL version literally returns `signal_pending(current) ? 0 : 1)` and FreeBSD implements the same semantics, we can just do `!cv_wait_sig()` in place of `signal_pending(current)` to avoid unnecessarily calling it again. zfs_setattr() on FreeBSD version did not have error handling issue because the code was removed entirely from FreeBSD version. The error is from updating the attribute directory's files. After some thought, I decided to propapage errors on it to userspace. In zfs_secpolicy_tmp_snapshot(), we ignore a lack of permission from the first check in favor of checking three other permissions. I assume this is intentional. In zfs_create_fs(), the return value of zap_update() was not checked despite setting an important version number. I see no backward compatibility reason to permit failures, so we add an assertion to catch failures. Interestingly, Linux is still using ASSERT(error == 0) from OpenSolaris while FreeBSD has switched to the improved ASSERT0(error) from illumos, although illumos has yet to adopt it here. ASSERT(error == 0) was used on Linux while ASSERT0(error) was used on FreeBSD since the entire file needs conversion and that should be the subject of another patch. dnode_move()'s issue was caused by us not having implemented POINTER_IS_VALID() on Linux. We have a stub in `include/os/linux/spl/sys/kmem_cache.h` for it, when it really should be in `include/os/linux/spl/sys/kmem.h` to be consistent with Illumos/OpenSolaris. FreeBSD put both `POINTER_IS_VALID()` and `POINTER_INVALIDATE()` in `include/os/freebsd/spl/sys/kmem.h`, so we copy what it did. Whenever a report was in platform-specific code, I checked the FreeBSD version to see if it also applied to FreeBSD, but it was only relevant a few times. Lastly, the patch that enabled Clang's static analyzer to be run on the Linux kernel modules needs more work before it can be put into a PR. I plan to do that in the future as part of the on-going static analysis work that I am doing. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu> Closes #14380
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@ -40,6 +40,9 @@ extern void kmem_strfree(char *str);
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#define kmem_scnprintf scnprintf
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#define POINTER_IS_VALID(p) (!((uintptr_t)(p) & 0x3))
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#define POINTER_INVALIDATE(pp) (*(pp) = (void *)((uintptr_t)(*(pp)) | 0x1))
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/*
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* Memory allocation interfaces
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*/
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@ -98,9 +98,6 @@ extern struct rw_semaphore spl_kmem_cache_sem;
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#define SPL_MAX_KMEM_ORDER_NR_PAGES (KMALLOC_MAX_SIZE >> PAGE_SHIFT)
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#endif
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#define POINTER_IS_VALID(p) 0 /* Unimplemented */
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#define POINTER_INVALIDATE(pp) /* Unimplemented */
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typedef int (*spl_kmem_ctor_t)(void *, void *, int);
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typedef void (*spl_kmem_dtor_t)(void *, void *);
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@ -2414,7 +2414,6 @@ zfs_zaccess(znode_t *zp, int mode, int flags, boolean_t skipaclchk, cred_t *cr,
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* read_acl/read_attributes
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*/
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error = 0;
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ASSERT3U(working_mode, !=, 0);
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if ((working_mode & (ACE_READ_ACL|ACE_READ_ATTRIBUTES) &&
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@ -1708,6 +1708,7 @@ zfs_create_fs(objset_t *os, cred_t *cr, nvlist_t *zplprops, dmu_tx_t *tx)
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}
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ASSERT3U(version, !=, 0);
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error = zap_update(os, moid, ZPL_VERSION_STR, 8, 1, &version, tx);
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ASSERT0(error);
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/*
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* Create zap object used for SA attribute registration
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@ -791,10 +791,8 @@ spl_kmem_cache_create(const char *name, size_t size, size_t align,
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} else {
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unsigned long slabflags = 0;
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if (size > (SPL_MAX_KMEM_ORDER_NR_PAGES * PAGE_SIZE)) {
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rc = EINVAL;
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if (size > (SPL_MAX_KMEM_ORDER_NR_PAGES * PAGE_SIZE))
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goto out;
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}
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#if defined(SLAB_USERCOPY)
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/*
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@ -815,10 +813,8 @@ spl_kmem_cache_create(const char *name, size_t size, size_t align,
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skc->skc_linux_cache = kmem_cache_create(
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skc->skc_name, size, align, slabflags, NULL);
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#endif
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if (skc->skc_linux_cache == NULL) {
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rc = ENOMEM;
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if (skc->skc_linux_cache == NULL)
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goto out;
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}
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}
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down_write(&spl_kmem_cache_sem);
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@ -178,12 +178,11 @@ issig(int why)
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sigorsets(&set, &task->blocked, &set);
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spin_lock_irq(&task->sighand->siglock);
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int ret;
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#ifdef HAVE_DEQUEUE_SIGNAL_4ARG
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enum pid_type __type;
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if ((ret = dequeue_signal(task, &set, &__info, &__type)) != 0) {
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if (dequeue_signal(task, &set, &__info, &__type) != 0) {
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#else
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if ((ret = dequeue_signal(task, &set, &__info)) != 0) {
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if (dequeue_signal(task, &set, &__info) != 0) {
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#endif
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#ifdef HAVE_SIGNAL_STOP
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spin_unlock_irq(&task->sighand->siglock);
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@ -425,7 +425,7 @@ vdev_disk_dio_get(dio_request_t *dr)
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atomic_inc(&dr->dr_ref);
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}
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static int
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static void
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vdev_disk_dio_put(dio_request_t *dr)
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{
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int rc = atomic_dec_return(&dr->dr_ref);
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@ -449,14 +449,11 @@ vdev_disk_dio_put(dio_request_t *dr)
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zio_delay_interrupt(zio);
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}
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}
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return (rc);
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}
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BIO_END_IO_PROTO(vdev_disk_physio_completion, bio, error)
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{
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dio_request_t *dr = bio->bi_private;
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int rc;
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if (dr->dr_error == 0) {
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#ifdef HAVE_1ARG_BIO_END_IO_T
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@ -470,7 +467,7 @@ BIO_END_IO_PROTO(vdev_disk_physio_completion, bio, error)
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}
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/* Drop reference acquired by __vdev_disk_physio */
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rc = vdev_disk_dio_put(dr);
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vdev_disk_dio_put(dr);
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}
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static inline void
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@ -742,7 +739,7 @@ __vdev_disk_physio(struct block_device *bdev, zio_t *zio,
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if (dr->dr_bio_count > 1)
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blk_finish_plug(&plug);
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(void) vdev_disk_dio_put(dr);
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vdev_disk_dio_put(dr);
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return (error);
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}
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@ -2581,7 +2581,6 @@ zfs_fastaccesschk_execute(znode_t *zdp, cred_t *cr)
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}
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if (uid == KUID_TO_SUID(ZTOI(zdp)->i_uid)) {
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owner = B_TRUE;
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if (zdp->z_mode & S_IXUSR) {
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mutex_exit(&zdp->z_acl_lock);
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return (0);
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@ -2591,7 +2590,6 @@ zfs_fastaccesschk_execute(znode_t *zdp, cred_t *cr)
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}
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}
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if (groupmember(KGID_TO_SGID(ZTOI(zdp)->i_gid), cr)) {
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groupmbr = B_TRUE;
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if (zdp->z_mode & S_IXGRP) {
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mutex_exit(&zdp->z_acl_lock);
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return (0);
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@ -2720,7 +2718,6 @@ zfs_zaccess(znode_t *zp, int mode, int flags, boolean_t skipaclchk, cred_t *cr,
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* read_acl/read_attributes
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*/
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error = 0;
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ASSERT(working_mode != 0);
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if ((working_mode & (ACE_READ_ACL|ACE_READ_ATTRIBUTES) &&
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@ -721,7 +721,6 @@ zfs_create(znode_t *dzp, char *name, vattr_t *vap, int excl,
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if (have_acl)
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zfs_acl_ids_free(&acl_ids);
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have_acl = B_FALSE;
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/*
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* A directory entry already exists for this name.
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@ -2532,7 +2531,7 @@ zfs_setattr(znode_t *zp, vattr_t *vap, int flags, cred_t *cr, zuserns_t *mnt_ns)
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dmu_tx_commit(tx);
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if (attrzp) {
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if (err2 == 0 && handle_eadir)
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err2 = zfs_setattr_dir(attrzp);
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err = zfs_setattr_dir(attrzp);
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zrele(attrzp);
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}
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zfs_znode_update_vfs(zp);
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@ -495,13 +495,11 @@ zfs_set_inode_flags(znode_t *zp, struct inode *ip)
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void
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zfs_znode_update_vfs(znode_t *zp)
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{
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zfsvfs_t *zfsvfs;
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struct inode *ip;
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uint32_t blksize;
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u_longlong_t i_blocks;
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ASSERT(zp != NULL);
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zfsvfs = ZTOZSB(zp);
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ip = ZTOI(zp);
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/* Skip .zfs control nodes which do not exist on disk. */
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@ -1885,6 +1883,7 @@ zfs_create_fs(objset_t *os, cred_t *cr, nvlist_t *zplprops, dmu_tx_t *tx)
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}
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ASSERT(version != 0);
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error = zap_update(os, moid, ZPL_VERSION_STR, 8, 1, &version, tx);
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ASSERT(error == 0);
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/*
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* Create zap object used for SA attribute registration
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@ -628,7 +628,7 @@ fletcher_4_kstat_data(char *buf, size_t size, void *data)
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off += snprintf(buf + off, size - off, "%-17s", "fastest");
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off += snprintf(buf + off, size - off, "%-15s",
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fletcher_4_supp_impls[fastest_stat->native]->name);
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off += snprintf(buf + off, size - off, "%-15s\n",
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(void) snprintf(buf + off, size - off, "%-15s\n",
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fletcher_4_supp_impls[fastest_stat->byteswap]->name);
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} else {
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ptrdiff_t id = curr_stat - fletcher_4_stat_data;
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@ -637,7 +637,7 @@ fletcher_4_kstat_data(char *buf, size_t size, void *data)
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fletcher_4_supp_impls[id]->name);
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off += snprintf(buf + off, size - off, "%-15llu",
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(u_longlong_t)curr_stat->native);
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off += snprintf(buf + off, size - off, "%-15llu\n",
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(void) snprintf(buf + off, size - off, "%-15llu\n",
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(u_longlong_t)curr_stat->byteswap);
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}
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@ -380,8 +380,7 @@ zfs_zevent_wait(zfs_zevent_t *ze)
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break;
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}
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error = cv_wait_sig(&zevent_cv, &zevent_lock);
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if (signal_pending(current)) {
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if (cv_wait_sig(&zevent_cv, &zevent_lock) == 0) {
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error = SET_ERROR(EINTR);
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break;
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} else if (!list_is_empty(&zevent_list)) {
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@ -1081,7 +1081,7 @@ zfs_secpolicy_diff(zfs_cmd_t *zc, nvlist_t *innvl, cred_t *cr)
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(void) innvl;
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int error;
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if ((error = secpolicy_sys_config(cr, B_FALSE)) == 0)
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if (secpolicy_sys_config(cr, B_FALSE) == 0)
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return (0);
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error = zfs_secpolicy_write_perms(zc->zc_name, ZFS_DELEG_PERM_DIFF, cr);
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@ -1230,8 +1230,8 @@ zfs_secpolicy_tmp_snapshot(zfs_cmd_t *zc, nvlist_t *innvl, cred_t *cr)
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*/
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int error;
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if ((error = zfs_secpolicy_write_perms(zc->zc_name,
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ZFS_DELEG_PERM_DIFF, cr)) == 0)
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if (zfs_secpolicy_write_perms(zc->zc_name,
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ZFS_DELEG_PERM_DIFF, cr) == 0)
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return (0);
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error = zfs_secpolicy_snapshot_perms(zc->zc_name, cr);
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@ -1279,8 +1279,7 @@ get_nvlist(uint64_t nvl, uint64_t size, int iflag, nvlist_t **nvp)
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packed = vmem_alloc(size, KM_SLEEP);
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if ((error = ddi_copyin((void *)(uintptr_t)nvl, packed, size,
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iflag)) != 0) {
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if (ddi_copyin((void *)(uintptr_t)nvl, packed, size, iflag) != 0) {
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vmem_free(packed, size);
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return (SET_ERROR(EFAULT));
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}
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@ -2682,7 +2681,6 @@ zfs_set_prop_nvlist(const char *dsname, zprop_source_t source, nvlist_t *nvl,
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pair = NULL;
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while ((pair = nvlist_next_nvpair(genericnvl, pair)) != NULL) {
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const char *propname = nvpair_name(pair);
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err = 0;
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propval = pair;
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if (nvpair_type(pair) == DATA_TYPE_NVLIST) {
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@ -3095,7 +3093,7 @@ zfs_ioc_set_fsacl(zfs_cmd_t *zc)
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/*
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* Verify nvlist is constructed correctly
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*/
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if ((error = zfs_deleg_verify_nvlist(fsaclnv)) != 0) {
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if (zfs_deleg_verify_nvlist(fsaclnv) != 0) {
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nvlist_free(fsaclnv);
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return (SET_ERROR(EINVAL));
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}
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* traverse snapshots only, do not traverse children,
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* and skip the 'dsname'
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*/
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error = dmu_objset_find(dsname,
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(void) dmu_objset_find(dsname,
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zvol_create_snap_minor_cb, (void *)job,
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DS_FIND_SNAPSHOTS);
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}
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#define FSE_buildDTable_raw zfs_FSE_buildDTable_raw
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#define FSE_buildDTable_rle zfs_FSE_buildDTable_rle
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#define FSE_buildDTable zfs_FSE_buildDTable
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#define FSE_createDTable zfs_FSE_createDTable
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#define FSE_decompress_usingDTable zfs_FSE_decompress_usingDTable
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#define FSE_decompress_wksp zfs_FSE_decompress_wksp
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#define FSE_decompress zfs_FSE_decompress
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#define FSE_freeDTable zfs_FSE_freeDTable
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/* lib/common/pool.o: */
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#define POOL_add zfs_POOL_add
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/* Function templates */
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FSE_DTable* FSE_createDTable (unsigned tableLog)
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{
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if (tableLog > FSE_TABLELOG_ABSOLUTE_MAX) tableLog = FSE_TABLELOG_ABSOLUTE_MAX;
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return (FSE_DTable*)malloc( FSE_DTABLE_SIZE_U32(tableLog) * sizeof (U32) );
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}
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void FSE_freeDTable (FSE_DTable* dt)
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{
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free(dt);
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}
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size_t FSE_buildDTable(FSE_DTable* dt, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog)
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{
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void* const tdPtr = dt+1; /* because *dt is unsigned, 32-bits aligned on 32-bits */
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