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authorJeff Mahoney <jeffm@suse.com>2011-04-28 00:22:20 +0400
committerJames Bottomley <James.Bottomley@suse.de>2011-05-01 22:04:02 +0400
commite37c4913c555bd149eba3af953fb5d3a1686dfbd (patch)
treeba9fbba3ba75f4a1153825c7833f977f8c6d50c6
parent9c324b8ba8e3ee8772a0c716d557e1582699d481 (diff)
downloadlinux-e37c4913c555bd149eba3af953fb5d3a1686dfbd.tar.xz
[SCSI] iterate over devices individually for /proc/scsi/scsi
On systems with very large numbers (> 1600 or so) of SCSI devices, cat /proc/scsi/scsi ends up failing with -ENOMEM. This is due to the show routine simply iterating over all of the devices with bus_for_each_dev(), and trying to dump all of them into the buffer at the same time. On my test system (using scsi_debug with 4064 devices), the output ends up being ~ 632k, far more than kmalloc will typically allow. This patch defines its own seq_file opreations to iterate over the scsi devices.The result is that each show() operation only dumps ~ 180 bytes into the buffer at a time so we don't run out of memory. If the "Attached devices" header isn't required, we can dump the sfile->private bit completely. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Signed-off-by: James Bottomley <James.Bottomley@suse.de>
-rw-r--r--drivers/scsi/scsi_proc.c58
1 files changed, 52 insertions, 6 deletions
diff --git a/drivers/scsi/scsi_proc.c b/drivers/scsi/scsi_proc.c
index c99da926fdac..f46855cd853d 100644
--- a/drivers/scsi/scsi_proc.c
+++ b/drivers/scsi/scsi_proc.c
@@ -386,13 +386,59 @@ static ssize_t proc_scsi_write(struct file *file, const char __user *buf,
* @s: output goes here
* @p: not used
*/
-static int proc_scsi_show(struct seq_file *s, void *p)
+static int always_match(struct device *dev, void *data)
{
- seq_printf(s, "Attached devices:\n");
- bus_for_each_dev(&scsi_bus_type, NULL, s, proc_print_scsidevice);
- return 0;
+ return 1;
+}
+
+static inline struct device *next_scsi_device(struct device *start)
+{
+ struct device *next = bus_find_device(&scsi_bus_type, start, NULL,
+ always_match);
+ put_device(start);
+ return next;
}
+static void *scsi_seq_start(struct seq_file *sfile, loff_t *pos)
+{
+ struct device *dev = NULL;
+ loff_t n = *pos;
+
+ while ((dev = next_scsi_device(dev))) {
+ if (!n--)
+ break;
+ sfile->private++;
+ }
+ return dev;
+}
+
+static void *scsi_seq_next(struct seq_file *sfile, void *v, loff_t *pos)
+{
+ (*pos)++;
+ sfile->private++;
+ return next_scsi_device(v);
+}
+
+static void scsi_seq_stop(struct seq_file *sfile, void *v)
+{
+ put_device(v);
+}
+
+static int scsi_seq_show(struct seq_file *sfile, void *dev)
+{
+ if (!sfile->private)
+ seq_puts(sfile, "Attached devices:\n");
+
+ return proc_print_scsidevice(dev, sfile);
+}
+
+static const struct seq_operations scsi_seq_ops = {
+ .start = scsi_seq_start,
+ .next = scsi_seq_next,
+ .stop = scsi_seq_stop,
+ .show = scsi_seq_show
+};
+
/**
* proc_scsi_open - glue function
* @inode: not used
@@ -406,7 +452,7 @@ static int proc_scsi_open(struct inode *inode, struct file *file)
* We don't really need this for the write case but it doesn't
* harm either.
*/
- return single_open(file, proc_scsi_show, NULL);
+ return seq_open(file, &scsi_seq_ops);
}
static const struct file_operations proc_scsi_operations = {
@@ -415,7 +461,7 @@ static const struct file_operations proc_scsi_operations = {
.read = seq_read,
.write = proc_scsi_write,
.llseek = seq_lseek,
- .release = single_release,
+ .release = seq_release,
};
/**