src/patches/suse-2.6.27.31/patches.fixes/proc-scsi-scsi-fix.diff

   1 From: Jeff Mahoney <jeffm@suse.com>
   2 Subject: [PATCH] scsi: iterate over devices individually for /proc/scsi/scsi
   3 References: 263731
   4 Patch-mainline: Probably never, hch wants to kill /proc/scsi/scsi anyway.
   5
   6  On systems with very large numbers (> 1600 or so) of SCSI devices,
   7  cat /proc/scsi/scsi ends up failing with -ENOMEM. This is due to
   8  the show routine simply iterating over all of the devices with
   9  bus_for_each_dev(), and trying to dump all of them into the buffer
  10  at the same time. On my test system (using scsi_debug with 4064 devices),
  11  the output ends up being ~ 632k, far more than kmalloc will typically allow.
  12
  13  This patch defines its own seq_file opreations to iterate over the scsi
  14  devices.The result is that each show() operation only dumps ~ 180 bytes
  15  into the buffer at a time so we don't run out of memory.
  16
  17  If the "Attached devices" header isn't required, we can dump the
  18  sfile->private bit completely.
  19
  20 Signed-off-by: Jeff Mahoney <jeffm@suse.com>
  21
  22 ---
  23
  24  drivers/scsi/scsi_proc.c |   58 ++++++++++++++++++++++++++++++++++++++++++-----
  25  1 file changed, 52 insertions(+), 6 deletions(-)
  26
  27 --- a/drivers/scsi/scsi_proc.c
  28 +++ b/drivers/scsi/scsi_proc.c
  29 @@ -389,13 +389,59 @@ static ssize_t proc_scsi_write(struct fi
  30   * @s: output goes here
  31   * @p: not used
  32   */
  33 -static int proc_scsi_show(struct seq_file *s, void *p)
  34 +static int always_match(struct device *dev, void *data)
  35  {
  36 -       seq_printf(s, "Attached devices:\n");
  37 -       bus_for_each_dev(&scsi_bus_type, NULL, s, proc_print_scsidevice);
  38 -       return 0;
  39 +       return 1;
  40  }
  41
  42 +static inline struct device *next_scsi_device(struct device *start)
  43 +{
  44 +       struct device *next = bus_find_device(&scsi_bus_type, start, NULL,
  45 +                                             always_match);
  46 +       put_device(start);
  47 +       return next;
  48 +}
  49 +
  50 +static void *scsi_seq_start(struct seq_file *sfile, loff_t *pos)
  51 +{
  52 +       struct device *dev = NULL;
  53 +       loff_t n = *pos;
  54 +
  55 +       while ((dev = next_scsi_device(dev))) {
  56 +               if (!n--)
  57 +                       break;
  58 +               sfile->private++;
  59 +       }
  60 +       return dev;
  61 +}
  62 +
  63 +static void *scsi_seq_next(struct seq_file *sfile, void *v, loff_t *pos)
  64 +{
  65 +       (*pos)++;
  66 +       sfile->private++;
  67 +       return next_scsi_device(v);
  68 +}
  69 +
  70 +static void scsi_seq_stop(struct seq_file *sfile, void *v)
  71 +{
  72 +       put_device(v);
  73 +}
  74 +
  75 +static int scsi_seq_show(struct seq_file *sfile, void *dev)
  76 +{
  77 +       if (!sfile->private)
  78 +               seq_puts(sfile, "Attached devices:\n");
  79 +
  80 +       return proc_print_scsidevice(dev, sfile);
  81 +}
  82 +
  83 +static struct seq_operations scsi_seq_ops = {
  84 +       .start  = scsi_seq_start,
  85 +       .next   = scsi_seq_next,
  86 +       .stop   = scsi_seq_stop,
  87 +       .show   = scsi_seq_show
  88 +};
  89 +
  90  /**
  91   * proc_scsi_open - glue function
  92   * @inode: not used
  93 @@ -409,7 +455,7 @@ static int proc_scsi_open(struct inode *
  94          * We don't really need this for the write case but it doesn't
  95          * harm either.
  96          */
  97 -       return single_open(file, proc_scsi_show, NULL);
  98 +       return seq_open(file, &scsi_seq_ops);
  99  }
 100
 101  static const struct file_operations proc_scsi_operations = {
 102 @@ -418,7 +464,7 @@ static const struct file_operations proc
 103         .read           = seq_read,
 104         .write          = proc_scsi_write,
 105         .llseek         = seq_lseek,
 106 -       .release        = single_release,
 107 +       .release        = seq_release,
 108  };
 109
 110  /**