Remove kallsyms_lookup_name() wrapper

After the removable of get_vmalloc_info(), the unused global memory
variables, and the optional dcache/icache shrinkers there is no
longer a need for the kallsyms compatibility code.  This allows
us to eliminate another brittle area of the code by removing the
kernel upcall this functionality depended on for older kernels.

Signed-off-by: Brian Behlendorf <[email protected]>

2 files changed, 1 insertions, 122 deletions

diff --git a/module/spl/spl-generic.c b/module/spl/spl-generic.c
index dacd0e260..fd68789bc 100644
--- a/module/spl/spl-generic.c
+++ b/module/spl/spl-generic.c
@@ -59,11 +59,6 @@ MODULE_PARM_DESC(spl_hostid, "The system hostid.");
 proc_t p0 = { 0 };
 EXPORT_SYMBOL(p0);
 
-#ifndef HAVE_KALLSYMS_LOOKUP_NAME
-DECLARE_WAIT_QUEUE_HEAD(spl_kallsyms_lookup_name_waitq);
-kallsyms_lookup_name_t spl_kallsyms_lookup_name_fn = SYMBOL_POISON;
-#endif
-
 #if BITS_PER_LONG == 32
 /*
  * Support 64/64 => 64 division on a 32-bit platform.  While the kernel
@@ -490,64 +485,6 @@ zone_get_hostid(void *zone)
 }
 EXPORT_SYMBOL(zone_get_hostid);
 
-/*
- * The kallsyms_lookup_name() kernel function is not an exported symbol in
- * Linux 2.6.19 through 2.6.32 inclusive.
- *
- * This function replaces the functionality by performing an upcall to user
- * space where /proc/kallsyms is consulted for the requested address.
- *
- */
-#define GET_KALLSYMS_ADDR_CMD \
-	"exec 0</dev/null " \
-	"     1>/proc/sys/kernel/spl/kallsyms_lookup_name " \
-	"     2>/dev/null; " \
-	"awk  '{ if ( $3 == \"kallsyms_lookup_name\" ) { print $1 } }' " \
-	"     /proc/kallsyms "
-
-static int
-set_kallsyms_lookup_name(void)
-{
-#ifndef HAVE_KALLSYMS_LOOKUP_NAME
-	char *argv[] = { "/bin/sh",
-	                 "-c",
-			 GET_KALLSYMS_ADDR_CMD,
-	                 NULL };
-	char *envp[] = { "HOME=/",
-	                 "TERM=linux",
-	                 "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
-	                 NULL };
-	int rc;
-
-	rc = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
-
-	/*
-	 * Due to I/O buffering the helper may return successfully before
-	 * the proc handler has a chance to execute.  To catch this case
-	 * wait up to 1 second to verify spl_kallsyms_lookup_name_fn was
-	 * updated to a non SYMBOL_POISON value.
-	 */
-	if (rc == 0) {
-		rc = wait_event_timeout(spl_kallsyms_lookup_name_waitq,
-		    spl_kallsyms_lookup_name_fn != SYMBOL_POISON, HZ);
-		if (rc == 0)
-			rc = -ETIMEDOUT;
-		else if (spl_kallsyms_lookup_name_fn == SYMBOL_POISON)
-			rc = -EFAULT;
-		else
-			rc = 0;
-	}
-
-	if (rc)
-		printk("SPL: Failed user helper '%s %s %s', rc = %d\n",
-		       argv[0], argv[1], argv[2], rc);
-
-	return (rc);
-#else
-	return (0);
-#endif /* HAVE_KALLSYMS_LOOKUP_NAME */
-}
-
 static int
 __init spl_init(void)
 {
@@ -583,14 +520,10 @@ __init spl_init(void)
 	if ((rc = spl_zlib_init()))
 		SGOTO(out9, rc);
 
-	if ((rc = set_kallsyms_lookup_name()))
-		SGOTO(out10, rc = -EADDRNOTAVAIL);
-
 	printk(KERN_NOTICE "SPL: Loaded module v%s-%s%s\n", SPL_META_VERSION,
 	       SPL_META_RELEASE, SPL_DEBUG_STR);
 	SRETURN(rc);
-out10:
-	spl_zlib_fini();
+
 out9:
 	spl_tsd_fini();
 out8:
diff --git a/module/spl/spl-proc.c b/module/spl/spl-proc.c
index 9c42c96ea..42733e0d7 100644
--- a/module/spl/spl-proc.c
+++ b/module/spl/spl-proc.c
@@ -409,51 +409,6 @@ SPL_PROC_HANDLER(proc_dohostid)
         SRETURN(rc);
 }
 
-#ifndef HAVE_KALLSYMS_LOOKUP_NAME
-SPL_PROC_HANDLER(proc_dokallsyms_lookup_name)
-{
-        int len, rc = 0;
-        char *end, str[32];
-	SENTRY;
-
-        if (write) {
-		/* This may only be set once at module load time */
-		if (spl_kallsyms_lookup_name_fn != SYMBOL_POISON)
-			SRETURN(-EEXIST);
-
-		/* We can't use spl_proc_doulongvec_minmax() in the write
-		 * case here because the address while a hex value has no
-		 * leading 0x which confuses the helper function. */
-                rc = proc_copyin_string(str, sizeof(str), buffer, *lenp);
-                if (rc < 0)
-                        SRETURN(rc);
-
-                spl_kallsyms_lookup_name_fn =
-			(kallsyms_lookup_name_t)simple_strtoul(str, &end, 16);
-		wake_up(&spl_kallsyms_lookup_name_waitq);
-
-		if (str == end)
-			SRETURN(-EINVAL);
-
-                *ppos += *lenp;
-        } else {
-                len = snprintf(str, sizeof(str), "%lx",
-			       (unsigned long)spl_kallsyms_lookup_name_fn);
-                if (*ppos >= len)
-                        rc = 0;
-                else
-                        rc = proc_copyout_string(buffer,*lenp,str+*ppos,"\n");
-
-                if (rc >= 0) {
-                        *lenp = rc;
-                        *ppos += rc;
-                }
-        }
-
-        SRETURN(rc);
-}
-#endif /* HAVE_KALLSYMS_LOOKUP_NAME */
-
 #ifdef DEBUG_KMEM
 static void
 slab_seq_show_headers(struct seq_file *f)
@@ -792,15 +747,6 @@ static struct ctl_table spl_table[] = {
                 .mode     = 0644,
                 .proc_handler = &proc_dohostid,
         },
-#ifndef HAVE_KALLSYMS_LOOKUP_NAME
-        {
-                .procname = "kallsyms_lookup_name",
-                .data     = &spl_kallsyms_lookup_name_fn,
-                .maxlen   = sizeof(unsigned long),
-                .mode     = 0644,
-                .proc_handler = &proc_dokallsyms_lookup_name,
-        },
-#endif
 #ifdef DEBUG_LOG
 	{
 		.procname = "debug",