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2014-10-02target: Add documentation on the target userspace pass-through driverAndy Grover
Describes the driver and its interface to make it possible for user programs to back a LIO-exported LUN. Thanks to Richard W. M. Jones for review, and supplementing this doc with the first two paragraphs. Signed-off-by: Andy Grover <agrover@redhat.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-10-02uio: Export definition of struct uio_deviceAndy Grover
In order to prevent a O(n) search of the filesystem to link up its uio node with its target configuration, TCMU needs to know the minor number that UIO assigned. Expose the definition of this struct so TCMU can access this field. Signed-off-by: Andy Grover <agrover@redhat.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-10-02target: Remove unneeded check in sbc_parse_cdbAndy Grover
The check of SCF_SCSI_DATA_CDB seems to be a remnant from before hch's refactoring of this function. There are no places where that flag is set that cmd->execute_cmd isn't also set. Signed-off-by: Andy Grover <agrover@redhat.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-10-01target: Fix queue full status NULL pointer for SCF_TRANSPORT_TASK_SENSEQuinn Tran
During temporary resource starvation at lower transport layer, command is placed on queue full retry path, which expose this problem. The TCM queue full handling of SCF_TRANSPORT_TASK_SENSE currently sends the same cmd twice to lower layer. The 1st time led to cmd normal free path. The 2nd time cause Null pointer access. This regression bug was originally introduced v3.1-rc code in the following commit: commit e057f53308a5f071556ee80586b99ee755bf07f5 Author: Christoph Hellwig <hch@infradead.org> Date: Mon Oct 17 13:56:41 2011 -0400 target: remove the transport_qf_callback se_cmd callback Signed-off-by: Quinn Tran <quinn.tran@qlogic.com> Signed-off-by: Saurav Kashyap <saurav.kashyap@qlogic.com> Cc: <stable@vger.kernel.org> # v3.1+ Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-10-01qla_target: rearrange struct qla_tgt_prmJoern Engel
On most (non-x86) 64bit platforms this will remove 8 padding bytes from the structure. Signed-off-by: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-10-01qla_target: improve qlt_unmap_sg()Joern Engel
Remove the inline attribute. Modern compilers ignore it and the function has grown beyond where inline made sense anyway. Remove the BUG_ON(!cmd->sg_mapped), and instead return if sg_mapped is not set. Every caller is doing this check, so we might as well have it in one place instead of four. Signed-off-by: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-10-01qla_target: make some global functions staticJoern Engel
Also removes the declarations from the header - including two declarations without function definitions or callers. Signed-off-by: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-10-01qla_target: remove unused parameterJoern Engel
Signed-off-by: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-10-01target: simplify core_tmr_abort_taskJoern Engel
list_for_each_entry_safe is necessary if list objects are deleted from the list while traversing it. Not the case here, so we can use the base list_for_each_entry variant. Signed-off-by: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-10-01target: encapsulate smp_mb__after_atomic()Joern Engel
The target code has a rather generous helping of smp_mb__after_atomic() throughout the code base. Most atomic operations were followed by one and none were preceded by smp_mb__before_atomic(), nor accompanied by a comment explaining the need for a barrier. Instead of trying to prove for every case whether or not it is needed, this patch introduces atomic_inc_mb() and atomic_dec_mb(), which explicitly include the memory barriers before and after the atomic operation. For now they are defined in a target header, although they could be of general use. Most of the existing atomic/mb combinations were replaced by the new helpers. In a few cases the atomic was sandwiched in spin_lock/spin_unlock and I simply removed the barrier. I suspect that in most cases the correct conversion would have been to drop the barrier. I also suspect that a few cases exist where a) the barrier was necessary and b) a second barrier before the atomic would have been necessary and got added by this patch. Signed-off-by: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-10-01target: remove some smp_mb__after_atomic()sJoern Engel
atomic_inc_return() already does an implicit memory barrier and the second case was moved from an atomic to a plain flag operation. If a barrier were needed in the second case, it would have to be smp_mb(), not a variant optimized away for x86 and other architectures. Signed-off-by: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-10-01target: simplify core_tmr_release_req()Joern Engel
And while at it, do minimal coding style fixes in the area. Signed-off-by: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-10-01target: Remove core_tpg_release_virtual_lun0 functionAndy Grover
Simple and just called from one place. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andy Grover <agrover@redhat.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-10-01target: Change core_dev_del_lun to take a se_lun instead of unpacked_lunAndy Grover
Remove core_tpg_pre_dellun entirely, since we don't need to get/check a pointer we already have. Nothing else can return an error, so core_dev_del_lun can return void. Rename core_tpg_post_dellun to remove_lun - a clearer name, now that pre_dellun is gone. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andy Grover <agrover@redhat.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-10-01target: core_tpg_post_dellun can return voidAndy Grover
Nothing in it can raise an error. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andy Grover <agrover@redhat.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-09-17target: fix unused shift in core_scsi3_pri_report_capabilitiesJoern Engel
Clearly a right-shift was meant. Effectively doesn't make a difference, as add_len is hard-coded to 8 and the high byte will be zero no matter which way you shift. But I hate leaving bad examples for others to copy. Found by coverity. Signed-off-by: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-09-17target: correctly handle match_int errors in FILEIO + PSCSIJoern Engel
This patch correctly handles match_int() errors in FILEIO + PSCSI backend parameter parsing, which can potentially fail due to a memory allocation failure or invalid argument. Found by coverity. Signed-off-by: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-09-17target: fix pr_out length in iscsi_parse_pr_out_transport_idJoern Engel
Old code in iscsi_parse_pr_out_transport_id() was obviously buggy and effectively ignored the high byte. Found by coverity. Signed-off-by: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-09-17target: simplify target_fabric_make_lun error pathJoern Engel
Coverity complained that lun_cg has been dereferenced in all paths leading to NULL check. It didn't mention that only a single path could lead there and the code can be simplified even further. Signed-off-by: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-09-17target: Fix memory leak on error in target_fabric_make_mappedlunJoern Engel
This patch fixes a memory leak on error in target_fabric_make_mappedlun(), where se_lun_acl memory does not get released on exit. Found by coverity. Signed-off-by: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-09-17target: Fix possible memory leak in aptpl_metadata parsingJoern Engel
Each case of match_strdup could leak memory if the same argument was present before. I am not too concerned, as it would require a non-sensical combination like "target_lun=foo target_lun=bar", done with root privileges and even then leak just a few bytes per instance. But arg_p is different, as it will always leak memory. Let's plug that one. And while at it, replace some &args[0] with args. Found by coverity. Signed-off-by: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-09-17iscsi-target: use strlcpy in iscsit_collect_login_statsJoern Engel
last_intr_fail_name is a fixed-size array and could theoretically overflow. In reality intrname->value doesn't seem to depend on untrusted input or be anywhere near 224 characters, so the overflow is pretty theoretical. But strlcpy is cheap enough. Found by coverity. Signed-off-by: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-09-17iscsi-target: remove unnecessary check in iscsit_setup_np error pathJoern Engel
Found by coverity. At this point sock is non-NULL, so the check to unnecessary. Signed-off-by: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-09-17iscsi-target: Drop duplicate __iscsi_target_login_thread checkNicholas Bellinger
This patch drops the now duplicate + unnecessary check for -ENODEV from iscsi_transport->iscsit_accept_np() for jumping to out:, or immediately returning 1 in __iscsi_target_login_thread() code. Since commit 81a9c5e72b the jump to out: and returning 1 have the same effect, and end up hitting the ISCSI_NP_THREAD_SHUTDOWN check regardless at the top of __iscsi_target_login_thread() during next loop iteration. So that said, it's safe to go ahead and remove this duplicate check. Reported-by: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-09-17iscsi-target: simplify return statementJoern Engel
The return statement cannot be reached without either recovery or dump being set to 1. Therefore the condition always evaluates to true and recovery and dump are useless variables. Found by Coverity. Signed-off-by: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-09-17iscsi-target: remove always-true conditionsJoern Engel
Found by coverity. InitiatorName and InitiatorAlias are static arrays and therefore always non-NULL. At some point in the past they may have been dynamically allocated, but for current code the condition is useless. If the intent was to check InitiatorName[0] instead, I cannot find a use for that either. Let's get rid of it. Signed-off-by: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-09-17iscsi-target: remove unused debug codeJoern Engel
Last user of buf was removed with c6037cc546ca. While at it, free_cpumask_var() handles a NULL argument just fine, so remove the conditionals. Signed-off-by: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-09-15target: target_core_ua_h: Add #define of include guardRasmus Villemoes
Clearly the file was meant to contain an include guard, but it was missing the #define part. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-09-15tcm_fc: Replace rcu_assign_pointer() with RCU_INIT_POINTER()Andreea-Cristina Bernat
The use of "rcu_assign_pointer()" is NULLing out the pointer. According to RCU_INIT_POINTER()'s block comment: "1. This use of RCU_INIT_POINTER() is NULLing out the pointer" it is better to use it instead of rcu_assign_pointer() because it has a smaller overhead. The following Coccinelle semantic patch was used: @@ @@ - rcu_assign_pointer + RCU_INIT_POINTER (..., NULL) Signed-off-by: Andreea-Cristina Bernat <bernat.ada@gmail.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-09-15target/configfs: Remove unnecessary null testHimangi Saraogi
This patch removes the null test on lun_cg. lun_cg is initialized at the beginning of the function to &lun->lun_group. Since lun_cg is dereferenced prior to the null test, it must be a valid pointer. The following Coccinelle script is used for detecting the change: @r@ expression e,f; identifier g,y; statement S1,S2; @@ *e = &f->g <+... f->y ...+> *if (e != NULL || ...) S1 else S2 Signed-off-by: Himangi Saraogi <himangi774@gmail.com> Acked-by: Julia Lawall <julia.lawall@lip6.fr> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2014-09-14Linux 3.17-rc5Linus Torvalds
2014-09-14Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs fixes from Al Viro: "double iput() on failure exit in lustre, racy removal of spliced dentries from ->s_anon in __d_materialise_dentry() plus a bunch of assorted RCU pathwalk fixes" The RCU pathwalk fixes end up fixing a couple of cases where we incorrectly dropped out of RCU walking, due to incorrect initialization and testing of the sequence locks in some corner cases. Since dropping out of RCU walk mode forces the slow locked accesses, those corner cases slowed down quite dramatically. * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: be careful with nd->inode in path_init() and follow_dotdot_rcu() don't bugger nd->seq on set_root_rcu() from follow_dotdot_rcu() fix bogus read_seqretry() checks introduced in b37199e move the call of __d_drop(anon) into __d_materialise_unique(dentry, anon) [fix] lustre: d_make_root() does iput() on dentry allocation failure
2014-09-14vfs: avoid non-forwarding large load after small store in path lookupLinus Torvalds
The performance regression that Josef Bacik reported in the pathname lookup (see commit 99d263d4c5b2 "vfs: fix bad hashing of dentries") made me look at performance stability of the dcache code, just to verify that the problem was actually fixed. That turned up a few other problems in this area. There are a few cases where we exit RCU lookup mode and go to the slow serializing case when we shouldn't, Al has fixed those and they'll come in with the next VFS pull. But my performance verification also shows that link_path_walk() turns out to have a very unfortunate 32-bit store of the length and hash of the name we look up, followed by a 64-bit read of the combined hash_len field. That screws up the processor store to load forwarding, causing an unnecessary hickup in this critical routine. It's caused by the ugly calling convention for the "hash_name()" function, and easily fixed by just making hash_name() fill in the whole 'struct qstr' rather than passing it a pointer to just the hash value. With that, the profile for this function looks much smoother. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-09-14Merge branch 'parisc-3.17-1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux Pull parisc updates from Helge Deller: "The most important patch is a new Light Weigth Syscall (LWS) for 8, 16, 32 and 64 bit atomic CAS operations which is required in order to be able to implement the atomic gcc builtins on our platform. Other than that, we wire up the seccomp, getrandom and memfd_create syscalls, fixes a minor off-by-one bug and a wrong printk string" * 'parisc-3.17-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux: parisc: Implement new LWS CAS supporting 64 bit operations. parisc: Wire up seccomp, getrandom and memfd_create syscalls parisc: dino: fix %d confusingly prefixed with 0x in format string parisc: sys_hpux: NUL terminator is one past the end
2014-09-14be careful with nd->inode in path_init() and follow_dotdot_rcu()Al Viro
in the former we simply check if dentry is still valid after picking its ->d_inode; in the latter we fetch ->d_inode in the same places where we fetch dentry and its ->d_seq, under the same checks. Cc: stable@vger.kernel.org # 2.6.38+ Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-09-14don't bugger nd->seq on set_root_rcu() from follow_dotdot_rcu()Al Viro
return the value instead, and have path_init() do the assignment. Broken by "vfs: Fix absolute RCU path walk failures due to uninitialized seq number", which was Cc-stable with 2.6.38+ as destination. This one should go where it went. To avoid dummy value returned in case when root is already set (it would do no harm, actually, since the only caller that doesn't ignore the return value is guaranteed to have nd->root *not* set, but it's more obvious that way), lift the check into callers. And do the same to set_root(), to keep them in sync. Cc: stable@vger.kernel.org # 2.6.38+ Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-09-14Merge tag 'ntb-3.17' of git://github.com/jonmason/ntbLinus Torvalds
Pull ntb driver bugfixes from Jon Mason: "NTB driver fixes for queue spread and buffer alignment. Also, update to MAINTAINERS to reflect new e-mail address" * tag 'ntb-3.17' of git://github.com/jonmason/ntb: ntb: Add alignment check to meet hardware requirement MAINTAINERS: update NTB info NTB: correct the spread of queues over mw's
2014-09-14Merge branch 'irq-urgent-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull ARM irq chip fixes from Thomas Gleixner: "Another pile of ARM specific irq chip fixlets: - off by one bugs in the crossbar driver - missing annotations - a bunch of "make it compile" updates I pulled the lot today from Jason, but it has been in -next for at least a week" * 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: irqchip: gic-v3: Declare rdist as __percpu pointer to __iomem pointer irqchip: gic: Make gic_default_routable_irq_domain_ops static irqchip: exynos-combiner: Fix compilation error on ARM64 irqchip: crossbar: Off by one bugs in init irqchip: gic-v3: Tag all low level accessors __maybe_unused irqchip: gic-v3: Only define gic_peek_irq() when building SMP
2014-09-14Merge tag 'irqchip-urgent-3.17' of ↵Thomas Gleixner
git://git.infradead.org/users/jcooper/linux into irq/urgent irqchip fixes for v3.17 from Jason Cooper - GIC/GICV3: Various fixlets - crossbar: Fix off-by-one bug - exynos-combiner: Fix arm64 build error
2014-09-14ntb: Add alignment check to meet hardware requirementDave Jiang
The NTB translate register must have the value to be BAR size aligned. This alignment check make sure that the DMA memory allocated has the proper alignment. Another requirement for NTB to function properly with memory window BAR size greater or equal to 4M is to use the CMA feature in 3.16 kernel with the appropriate CONFIG_CMA_ALIGNMENT and CONFIG_CMA_SIZE_MBYTES set. Signed-off-by: Dave Jiang <dave.jiang@intel.com> Signed-off-by: Jon Mason <jdmason@kudzu.us>
2014-09-14MAINTAINERS: update NTB infoJon Mason
Update my contact info to my personal email address and add Dave Jiang. Signed-off-by: Jon Mason <jon.mason@intel.com> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
2014-09-14NTB: correct the spread of queues over mw'sJon Mason
The detection of an uneven number of queues on the given memory windows was not correct. The mw_num is zero based and the mod should be division to spread them evenly over the mw's. Signed-off-by: Jon Mason <jon.mason@intel.com>
2014-09-13fix bogus read_seqretry() checks introduced in b37199eAl Viro
read_seqretry() returns true on mismatch, not on match... Cc: stable@vger.kernel.org # 3.15+ Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-09-13move the call of __d_drop(anon) into __d_materialise_unique(dentry, anon)Al Viro
and lock the right list there Cc: stable@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-09-13[fix] lustre: d_make_root() does iput() on dentry allocation failureAl Viro
double-free is a bad thing Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-09-13Merge branches 'locking-urgent-for-linus' and 'timers-urgent-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull futex and timer fixes from Thomas Gleixner: "A oneliner bugfix for the jinxed futex code: - Drop hash bucket lock in the error exit path. I really could slap myself for intruducing that bug while fixing all the other horror in that code three month ago ... and the timer department is not too proud about the following fixes: - Deal with a long standing rounding bug in the timeval to jiffies conversion. It's a real issue and this fix fell through the cracks for quite some time. - Another round of alarmtimer fixes. Finally this code gets used more widely and the subtle issues hidden for quite some time are noticed and fixed. Nothing really exciting, just the itty bitty details which bite the serious users here and there" * 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: futex: Unlock hb->lock in futex_wait_requeue_pi() error path * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: alarmtimer: Lock k_itimer during timer callback alarmtimer: Do not signal SIGEV_NONE timers alarmtimer: Return relative times in timer_gettime jiffies: Fix timeval conversion to jiffies
2014-09-13parisc: Implement new LWS CAS supporting 64 bit operations.Guy Martin
The current LWS cas only works correctly for 32bit. The new LWS allows for CAS operations of variable size. Signed-off-by: Guy Martin <gmsoft@tuxicoman.be> Cc: <stable@vger.kernel.org> # 3.13+ Signed-off-by: Helge Deller <deller@gmx.de>
2014-09-13vfs: fix bad hashing of dentriesLinus Torvalds
Josef Bacik found a performance regression between 3.2 and 3.10 and narrowed it down to commit bfcfaa77bdf0 ("vfs: use 'unsigned long' accesses for dcache name comparison and hashing"). He reports: "The test case is essentially for (i = 0; i < 1000000; i++) mkdir("a$i"); On xfs on a fio card this goes at about 20k dir/sec with 3.2, and 12k dir/sec with 3.10. This is because we spend waaaaay more time in __d_lookup on 3.10 than in 3.2. The new hashing function for strings is suboptimal for < sizeof(unsigned long) string names (and hell even > sizeof(unsigned long) string names that I've tested). I broke out the old hashing function and the new one into a userspace helper to get real numbers and this is what I'm getting: Old hash table had 1000000 entries, 0 dupes, 0 max dupes New hash table had 12628 entries, 987372 dupes, 900 max dupes We had 11400 buckets with a p50 of 30 dupes, p90 of 240 dupes, p99 of 567 dupes for the new hash My test does the hash, and then does the d_hash into a integer pointer array the same size as the dentry hash table on my system, and then just increments the value at the address we got to see how many entries we overlap with. As you can see the old hash function ended up with all 1 million entries in their own bucket, whereas the new one they are only distributed among ~12.5k buckets, which is why we're using so much more CPU in __d_lookup". The reason for this hash regression is two-fold: - On 64-bit architectures the down-mixing of the original 64-bit word-at-a-time hash into the final 32-bit hash value is very simplistic and suboptimal, and just adds the two 32-bit parts together. In particular, because there is no bit shuffling and the mixing boundary is also a byte boundary, similar character patterns in the low and high word easily end up just canceling each other out. - the old byte-at-a-time hash mixed each byte into the final hash as it hashed the path component name, resulting in the low bits of the hash generally being a good source of hash data. That is not true for the word-at-a-time case, and the hash data is distributed among all the bits. The fix is the same in both cases: do a better job of mixing the bits up and using as much of the hash data as possible. We already have the "hash_32|64()" functions to do that. Reported-by: Josef Bacik <jbacik@fb.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Chris Mason <clm@fb.com> Cc: linux-fsdevel@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-09-13Make hash_64() use a 64-bit multiply when appropriateLinus Torvalds
The hash_64() function historically does the multiply by the GOLDEN_RATIO_PRIME_64 number with explicit shifts and adds, because unlike the 32-bit case, gcc seems unable to turn the constant multiply into the more appropriate shift and adds when required. However, that means that we generate those shifts and adds even when the architecture has a fast multiplier, and could just do it better in hardware. Use the now-cleaned-up CONFIG_ARCH_HAS_FAST_MULTIPLIER (together with "is it a 64-bit architecture") to decide whether to use an integer multiply or the explicit sequence of shift/add instructions. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-09-13Make ARCH_HAS_FAST_MULTIPLIER a real config variableLinus Torvalds
It used to be an ad-hoc hack defined by the x86 version of <asm/bitops.h> that enabled a couple of library routines to know whether an integer multiply is faster than repeated shifts and additions. This just makes it use the real Kconfig system instead, and makes x86 (which was the only architecture that did this) select the option. NOTE! Even for x86, this really is kind of wrong. If we cared, we would probably not enable this for builds optimized for netburst (P4), where shifts-and-adds are generally faster than multiplies. This patch does *not* change that kind of logic, though, it is purely a syntactic change with no code changes. This was triggered by the fact that we have other places that really want to know "do I want to expand multiples by constants by hand or not", particularly the hash generation code. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>