1. 09 11月, 2013 37 次提交
  2. 08 11月, 2013 3 次提交
    • C
      block: Replace __get_cpu_var uses · 170d800a
      Christoph Lameter 提交于
      __get_cpu_var() is used for multiple purposes in the kernel source. One of
      them is address calculation via the form &__get_cpu_var(x).  This calculates
      the address for the instance of the percpu variable of the current processor
      based on an offset.
      
      Other use cases are for storing and retrieving data from the current
      processors percpu area.  __get_cpu_var() can be used as an lvalue when
      writing data or on the right side of an assignment.
      
      __get_cpu_var() is defined as :
      
      #define __get_cpu_var(var) (*this_cpu_ptr(&(var)))
      
      __get_cpu_var() always only does an address determination. However, store
      and retrieve operations could use a segment prefix (or global register on
      other platforms) to avoid the address calculation.
      
      this_cpu_write() and this_cpu_read() can directly take an offset into a
      percpu area and use optimized assembly code to read and write per cpu
      variables.
      
      This patch converts __get_cpu_var into either an explicit address
      calculation using this_cpu_ptr() or into a use of this_cpu operations that
      use the offset.  Thereby address calculations are avoided and less registers
      are used when code is generated.
      
      At the end of the patch set all uses of __get_cpu_var have been removed so
      the macro is removed too.
      
      The patch set includes passes over all arches as well. Once these operations
      are used throughout then specialized macros can be defined in non -x86
      arches as well in order to optimize per cpu access by f.e.  using a global
      register that may be set to the per cpu base.
      
      Transformations done to __get_cpu_var()
      
      1. Determine the address of the percpu instance of the current processor.
      
      	DEFINE_PER_CPU(int, y);
      	int *x = &__get_cpu_var(y);
      
          Converts to
      
      	int *x = this_cpu_ptr(&y);
      
      2. Same as #1 but this time an array structure is involved.
      
      	DEFINE_PER_CPU(int, y[20]);
      	int *x = __get_cpu_var(y);
      
          Converts to
      
      	int *x = this_cpu_ptr(y);
      
      3. Retrieve the content of the current processors instance of a per cpu
      variable.
      
      	DEFINE_PER_CPU(int, y);
      	int x = __get_cpu_var(y)
      
         Converts to
      
      	int x = __this_cpu_read(y);
      
      4. Retrieve the content of a percpu struct
      
      	DEFINE_PER_CPU(struct mystruct, y);
      	struct mystruct x = __get_cpu_var(y);
      
         Converts to
      
      	memcpy(&x, this_cpu_ptr(&y), sizeof(x));
      
      5. Assignment to a per cpu variable
      
      	DEFINE_PER_CPU(int, y)
      	__get_cpu_var(y) = x;
      
         Converts to
      
      	this_cpu_write(y, x);
      
      6. Increment/Decrement etc of a per cpu variable
      
      	DEFINE_PER_CPU(int, y);
      	__get_cpu_var(y)++
      
         Converts to
      
      	this_cpu_inc(y)
      Signed-off-by: NChristoph Lameter <cl@linux.com>
      Signed-off-by: NJens Axboe <axboe@kernel.dk>
      170d800a
    • M
      bdi: test bdi_init failure · 8077c0d9
      Mikulas Patocka 提交于
      There were two places where return value from bdi_init was not tested.
      Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
      Acked-by: NTejun Heo <tj@kernel.org>
      Signed-off-by: NJens Axboe <axboe@kernel.dk>
      8077c0d9
    • M
      block: fix a probe argument to blk_register_region · a207f593
      Mikulas Patocka 提交于
      The probe function is supposed to return NULL on failure (as we can see in
      kobj_lookup: kobj = probe(dev, index, data); ... if (kobj) return kobj;
      
      However, in loop and brd, it returns negative error from ERR_PTR.
      
      This causes a crash if we simulate disk allocation failure and run
      less -f /dev/loop0 because the negative number is interpreted as a pointer:
      
      BUG: unable to handle kernel NULL pointer dereference at 00000000000002b4
      IP: [<ffffffff8118b188>] __blkdev_get+0x28/0x450
      PGD 23c677067 PUD 23d6d1067 PMD 0
      Oops: 0000 [#1] PREEMPT SMP
      Modules linked in: loop hpfs nvidia(PO) ip6table_filter ip6_tables uvesafb cfbcopyarea cfbimgblt cfbfillrect fbcon font bitblit fbcon_rotate fbcon_cw fbcon_ud fbcon_ccw softcursor fb fbdev msr ipt_MASQUERADE iptable_nat nf_nat_ipv4 nf_conntrack_ipv4 nf_defrag_ipv4 xt_state ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge stp llc tun ipv6 cpufreq_stats cpufreq_ondemand cpufreq_userspace cpufreq_powersave cpufreq_conservative hid_generic spadfs usbhid hid fuse raid0 snd_usb_audio snd_pcm_oss snd_mixer_oss md_mod snd_pcm snd_timer snd_page_alloc snd_hwdep snd_usbmidi_lib dmi_sysfs snd_rawmidi nf_nat_ftp nf_nat nf_conntrack_ftp nf_conntrack snd soundcore lm85 hwmon_vid ohci_hcd ehci_pci ehci_hcd serverworks sata_svw libata acpi_cpufreq freq_table mperf ide_core usbcore kvm_amd kvm tg3 i2c_piix4 libphy microcode e100 usb_common ptp skge i2c_core pcspkr k10temp evdev floppy hwmon pps_core mii rtc_cmos button processor unix [last unloaded: nvidia]
      CPU: 1 PID: 6831 Comm: less Tainted: P        W  O 3.10.15-devel #18
      Hardware name: empty empty/S3992-E, BIOS 'V1.06   ' 06/09/2009
      task: ffff880203cc6bc0 ti: ffff88023e47c000 task.ti: ffff88023e47c000
      RIP: 0010:[<ffffffff8118b188>]  [<ffffffff8118b188>] __blkdev_get+0x28/0x450
      RSP: 0018:ffff88023e47dbd8  EFLAGS: 00010286
      RAX: ffffffffffffff74 RBX: ffffffffffffff74 RCX: 0000000000000000
      RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
      RBP: ffff88023e47dc18 R08: 0000000000000002 R09: 0000000000000000
      R10: 0000000000000000 R11: 0000000000000000 R12: ffff88023f519658
      R13: ffffffff8118c300 R14: 0000000000000000 R15: ffff88023f519640
      FS:  00007f2070bf7700(0000) GS:ffff880247400000(0000) knlGS:0000000000000000
      CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
      CR2: 00000000000002b4 CR3: 000000023da1d000 CR4: 00000000000007e0
      DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
      DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
      Stack:
       0000000000000002 0000001d00000000 000000003e47dc50 ffff88023f519640
       ffff88043d5bb668 ffffffff8118c300 ffff88023d683550 ffff88023e47de60
       ffff88023e47dc98 ffffffff8118c10d 0000001d81605698 0000000000000292
      Call Trace:
       [<ffffffff8118c300>] ? blkdev_get_by_dev+0x60/0x60
       [<ffffffff8118c10d>] blkdev_get+0x1dd/0x370
       [<ffffffff8118c300>] ? blkdev_get_by_dev+0x60/0x60
       [<ffffffff813cea6c>] ? _raw_spin_unlock+0x2c/0x50
       [<ffffffff8118c300>] ? blkdev_get_by_dev+0x60/0x60
       [<ffffffff8118c365>] blkdev_open+0x65/0x80
       [<ffffffff8114d12e>] do_dentry_open.isra.18+0x23e/0x2f0
       [<ffffffff8114d214>] finish_open+0x34/0x50
       [<ffffffff8115e122>] do_last.isra.62+0x2d2/0xc50
       [<ffffffff8115eb58>] path_openat.isra.63+0xb8/0x4d0
       [<ffffffff81115a8e>] ? might_fault+0x4e/0xa0
       [<ffffffff8115f4f0>] do_filp_open+0x40/0x90
       [<ffffffff813cea6c>] ? _raw_spin_unlock+0x2c/0x50
       [<ffffffff8116db85>] ? __alloc_fd+0xa5/0x1f0
       [<ffffffff8114e45f>] do_sys_open+0xef/0x1d0
       [<ffffffff8114e559>] SyS_open+0x19/0x20
       [<ffffffff813cff16>] system_call_fastpath+0x1a/0x1f
      Code: 44 00 00 55 48 89 e5 41 57 49 89 ff 41 56 41 89 d6 41 55 41 54 4c 8d 67 18 53 48 83 ec 18 89 75 cc e9 f2 00 00 00 0f 1f 44 00 00 <48> 8b 80 40 03 00 00 48 89 df 4c 8b 68 58 e8 d5
      a4 07 00 44 89
      RIP  [<ffffffff8118b188>] __blkdev_get+0x28/0x450
       RSP <ffff88023e47dbd8>
      CR2: 00000000000002b4
      ---[ end trace bb7f32dbf02398dc ]---
      
      The brd change should be backported to stable kernels starting with 2.6.25.
      The loop change should be backported to stable kernels starting with 2.6.22.
      Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
      Acked-by: NTejun Heo <tj@kernel.org>
      Cc: stable@kernel.org	# 2.6.22+
      Signed-off-by: NJens Axboe <axboe@kernel.dk>
      a207f593