Clean up check_pf allocation pattern. addresses
diff mbox

Message ID 20140325214344.GA23074@domone.podge
State New
Headers show

Commit Message

Ondřej Bílka March 25, 2014, 9:43 p.m. UTC
On Mon, Mar 24, 2014 at 07:14:08PM +0100, Andreas Schwab wrote:
> Ondřej Bílka <neleai@seznam.cz> writes:
> 
> > As far as I recall there was a similar patch that did not get in.
> >
> > After I reviewed that I noticed that you could drop alloca altogether.
> >
> > Its only used to construct a single linked list and then copy it to
> > malloced array. Faster way would be to malloc array directly, realloc as
> > necessary.
> 
> Sorry, I missed it when I searched for __check_pf.  Could you rebase
> your patch?  This issue is orthogonal to the alloca issue.
> 
Yes, here it is.

I dropped a malloc/free of buf because it only once allocates one page and
check if this is small enough does not make lot of sense.

Second part consist from replacing a creating linked list and copying it to
result by directly creating a result.

	* sysdeps/unix/sysv/linux/check_pf.c (make_pf): Simplify
	allocation strategy.

Comments

Andreas Schwab March 26, 2014, 9:53 a.m. UTC | #1
Ondřej Bílka <neleai@seznam.cz> writes:

> diff --git a/sysdeps/unix/sysv/linux/check_pf.c b/sysdeps/unix/sysv/linux/check_pf.c
> index e6a12ed..40b1af2 100644
> --- a/sysdeps/unix/sysv/linux/check_pf.c
> +++ b/sysdeps/unix/sysv/linux/check_pf.c
> @@ -106,6 +106,12 @@ cache_valid_p (void)
>  static struct cached_data *
>  make_request (int fd, pid_t pid)
>  {
> +

Extra empty line.

> @@ -241,40 +230,36 @@ make_request (int fd, pid_t pid)
>  		    }
>  		}
>  
> -	      struct in6ailist *newp;
> -	      if (__libc_use_alloca (alloca_used + sizeof (*newp)))
> +	      if (result_len == 0 || result_len == result_cap)
>  		{
> -		  newp = alloca_account (sizeof (*newp), alloca_used);
> -		  newp->use_malloc = false;
> + 		  result_cap = 2 * result_cap;
> +		  result = realloc (result, sizeof (*result)
> +			+ result_cap * sizeof (struct in6addrinfo));

Wrong indent.

> +	      info->flags = (((ifam->ifa_flags
>  				    & (IFA_F_DEPRECATED

Wrong indent.

Andreas.

Patch
diff mbox

diff --git a/sysdeps/unix/sysv/linux/check_pf.c b/sysdeps/unix/sysv/linux/check_pf.c
index e6a12ed..40b1af2 100644
--- a/sysdeps/unix/sysv/linux/check_pf.c
+++ b/sysdeps/unix/sysv/linux/check_pf.c
@@ -106,6 +106,12 @@  cache_valid_p (void)
 static struct cached_data *
 make_request (int fd, pid_t pid)
 {
+
+  struct cached_data *result = NULL;
+
+  size_t result_len = 0;
+  size_t result_cap = 32;
+
   struct req
   {
     struct nlmsghdr nlh;
@@ -137,20 +143,9 @@  make_request (int fd, pid_t pid)
 #else
   const size_t buf_size = __getpagesize ();
 #endif
-  bool use_malloc = false;
   char *buf;
-  size_t alloca_used = 0;
 
-  if (__libc_use_alloca (buf_size))
-    buf = alloca_account (buf_size, alloca_used);
-  else
-    {
-      buf = malloc (buf_size);
-      if (buf != NULL)
-	use_malloc = true;
-      else
-	goto out_fail;
-    }
+  buf = alloca (buf_size);
 
   struct iovec iov = { buf, buf_size };
 
@@ -160,13 +155,7 @@  make_request (int fd, pid_t pid)
     goto out_fail;
 
   bool done = false;
-  struct in6ailist
-  {
-    struct in6addrinfo info;
-    struct in6ailist *next;
-    bool use_malloc;
-  } *in6ailist = NULL;
-  size_t in6ailistlen = 0;
+
   bool seen_ipv4 = false;
   bool seen_ipv6 = false;
 
@@ -182,10 +171,10 @@  make_request (int fd, pid_t pid)
 
       ssize_t read_len = TEMP_FAILURE_RETRY (__recvmsg (fd, &msg, 0));
       if (read_len < 0)
-	goto out_fail2;
+	goto out_fail;
 
       if (msg.msg_flags & MSG_TRUNC)
-	goto out_fail2;
+	goto out_fail;
 
       struct nlmsghdr *nlmh;
       for (nlmh = (struct nlmsghdr *) buf;
@@ -241,40 +230,36 @@  make_request (int fd, pid_t pid)
 		    }
 		}
 
-	      struct in6ailist *newp;
-	      if (__libc_use_alloca (alloca_used + sizeof (*newp)))
+	      if (result_len == 0 || result_len == result_cap)
 		{
-		  newp = alloca_account (sizeof (*newp), alloca_used);
-		  newp->use_malloc = false;
+ 		  result_cap = 2 * result_cap;
+		  result = realloc (result, sizeof (*result)
+			+ result_cap * sizeof (struct in6addrinfo));
 		}
-	      else
-		{
-		  newp = malloc (sizeof (*newp));
-		  if (newp == NULL)
-		    goto out_fail2;
-		  newp->use_malloc = true;
-		}
-	      newp->info.flags = (((ifam->ifa_flags
+
+	      if (!result)
+		goto out_fail;
+
+	      struct in6addrinfo *info = &result->in6ai[result_len++]; 
+
+	      info->flags = (((ifam->ifa_flags
 				    & (IFA_F_DEPRECATED
 				       | IFA_F_OPTIMISTIC))
 				   ? in6ai_deprecated : 0)
 				  | ((ifam->ifa_flags
 				      & IFA_F_HOMEADDRESS)
 				     ? in6ai_homeaddress : 0));
-	      newp->info.prefixlen = ifam->ifa_prefixlen;
-	      newp->info.index = ifam->ifa_index;
+	      info->prefixlen = ifam->ifa_prefixlen;
+	      info->index = ifam->ifa_index;
 	      if (ifam->ifa_family == AF_INET)
 		{
-		  newp->info.addr[0] = 0;
-		  newp->info.addr[1] = 0;
-		  newp->info.addr[2] = htonl (0xffff);
-		  newp->info.addr[3] = *(const in_addr_t *) address;
+		  info->addr[0] = 0;
+		  info->addr[1] = 0;
+		  info->addr[2] = htonl (0xffff);
+		  info->addr[3] = *(const in_addr_t *) address;
 		}
 	      else
-		memcpy (newp->info.addr, address, sizeof (newp->info.addr));
-	      newp->next = in6ailist;
-	      in6ailist = newp;
-	      ++in6ailistlen;
+		memcpy (info->addr, address, sizeof (info->addr));
 	    }
 	  else if (nlmh->nlmsg_type == NLMSG_DONE)
 	    /* We found the end, leave the loop.  */
@@ -283,53 +268,29 @@  make_request (int fd, pid_t pid)
     }
   while (! done);
 
-  struct cached_data *result;
-  if (seen_ipv6 && in6ailist != NULL)
+  if (seen_ipv6 && result != NULL)
     {
-      result = malloc (sizeof (*result)
-		       + in6ailistlen * sizeof (struct in6addrinfo));
-      if (result == NULL)
-	goto out_fail2;
-
       result->timestamp = get_nl_timestamp ();
       result->usecnt = 2;
       result->seen_ipv4 = seen_ipv4;
       result->seen_ipv6 = true;
-      result->in6ailen = in6ailistlen;
-
-      do
-	{
-	  result->in6ai[--in6ailistlen] = in6ailist->info;
-	  struct in6ailist *next = in6ailist->next;
-	  if (in6ailist->use_malloc)
-	    free (in6ailist);
-	  in6ailist = next;
-	}
-      while (in6ailist != NULL);
+      result->in6ailen = result_len;
     }
   else
     {
+      free (result);
+
       atomic_add (&noai6ai_cached.usecnt, 2);
       noai6ai_cached.seen_ipv4 = seen_ipv4;
       noai6ai_cached.seen_ipv6 = seen_ipv6;
       result = &noai6ai_cached;
     }
 
-  if (use_malloc)
-    free (buf);
   return result;
 
- out_fail2:
-  while (in6ailist != NULL)
-    {
-      struct in6ailist *next = in6ailist->next;
-      if (in6ailist->use_malloc)
-	free (in6ailist);
-      in6ailist = next;
-    }
  out_fail:
-  if (use_malloc)
-    free (buf);
+
+  free (result);
   return NULL;
 }