procfs: retrieve both RS tables from RS at once

Previously, procfs would retrieve the rproc and rprocpub tables from
RS in two separate calls.  This allowed for a race condition where the
tables could change in between the calls, resulting in a panic in
procfs under certain circumstances.  RS now implements a new method
for getsysinfo that allows the retrieval of both tables at once.

Change-Id: I5ec22d25898361270c90e805a43fc6d76ad9e29d

diff --git a/minix/fs/procfs/service.c b/minix/fs/procfs/service.c
index 852332a480a0321965afe203292ac57ae99019b2..576472105f71dbd5995321fa23e651a57f368a6f 100644 (file)
--- a/minix/fs/procfs/service.c
+++ b/minix/fs/procfs/service.c
@@ -19,8 +19,11 @@ struct policies {
        enum policy supported;
 };
 
-static struct rprocpub rprocpub[NR_SYS_PROCS];
-static struct rproc rproc[NR_SYS_PROCS];
+static struct {
+       struct rproc proc[NR_SYS_PROCS];
+       struct rprocpub pub[NR_SYS_PROCS];
+} rproc;
+
 static struct policies policies[NR_SYS_PROCS];
 
 static struct inode *service_node;
@@ -132,9 +135,9 @@ service_get_policies(struct policies * pol, index_t slot)
        };
 
        /* Find the related policy, based on the file name of the service. */
-       ref_label = strrchr(rprocpub[slot].proc_name, '/');
+       ref_label = strrchr(rproc.pub[slot].proc_name, '/');
        if (NULL == ref_label)
-               ref_label = rprocpub[slot].proc_name;
+               ref_label = rproc.pub[slot].proc_name;
 
        memset(pol[slot].formatted, 0, MAX_POL_FORMAT_SZ);
        for(pos = 0; pos < (sizeof(def_pol) / sizeof(def_pol[0])); pos++) {
@@ -161,11 +164,15 @@ service_update(void)
        struct inode *node;
        struct inode_stat stat;
        index_t slot;
-
-       /* There is not much we can do if either of these calls fails. */
-       (void)getsysinfo(RS_PROC_NR, SI_PROCPUB_TAB, rprocpub,
-           sizeof(rprocpub));
-       (void)getsysinfo(RS_PROC_NR, SI_PROC_TAB, rproc, sizeof(rproc));
+       static int warned = FALSE;
+       int r;
+
+       /* There is not much we can do if this call fails. */
+       r = getsysinfo(RS_PROC_NR, SI_PROCALL_TAB, &rproc, sizeof(rproc));
+       if (r != OK && !warned) {
+               printf("PROCFS: unable to obtain RS tables (%d)\n", r);
+               warned = TRUE;
+       }
 
        /*
         * As with PIDs, we make two passes.  Delete first, then add.  This
@@ -180,8 +187,8 @@ service_update(void)
                 * If the slot is no longer in use, or the label name does not
                 * match, the node must be deleted.
                 */
-               if (!(rproc[slot].r_flags & RS_IN_USE) ||
-                   strcmp(get_inode_name(node), rprocpub[slot].label))
+               if (!(rproc.proc[slot].r_flags & RS_IN_USE) ||
+                   strcmp(get_inode_name(node), rproc.pub[slot].label))
                        delete_inode(node);
        }
 
@@ -191,11 +198,11 @@ service_update(void)
        stat.gid = SUPER_USER;
 
        for (slot = 0; slot < NR_SYS_PROCS; slot++) {
-               if (!(rproc[slot].r_flags & RS_IN_USE) ||
+               if (!(rproc.proc[slot].r_flags & RS_IN_USE) ||
                    get_inode_by_index(service_node, slot) != NULL)
                        continue;
 
-               node = add_inode(service_node, rprocpub[slot].label, slot,
+               node = add_inode(service_node, rproc.pub[slot].label, slot,
                    &stat, (index_t)0, (cbdata_t)slot);
 
                if (node == NULL)
@@ -277,8 +284,8 @@ service_read(struct inode * node)
                return;
 
        slot = get_inode_index(node);
-       rpub = &rprocpub[slot];
-       rp = &rproc[slot];
+       rpub = &rproc.pub[slot];
+       rp = &rproc.proc[slot];
 
        /* TODO: add a large number of other fields! */
        buf_printf("filename: %s\n", rpub->proc_name);

diff --git a/minix/include/minix/sysinfo.h b/minix/include/minix/sysinfo.h
index e63bb006e59d4520e0af46421249b2d780a9d2b8..1e4e2bbf9536928c3b0cc5da2f5a54bee5327d39 100644 (file)
--- a/minix/include/minix/sysinfo.h
+++ b/minix/include/minix/sysinfo.h
@@ -13,6 +13,7 @@ int getsysinfo(endpoint_t who, int what, void *where, size_t size);
 #define SI_DATA_STORE     5    /* get copy of data store mappings */
 #define SI_CALL_STATS     9    /* system call statistics */
 #define SI_PROCPUB_TAB    11   /* copy of public entries of process table */
+#define SI_PROCALL_TAB    12   /* copy of both private and public entries */
 
 #endif
 

diff --git a/minix/servers/rs/request.c b/minix/servers/rs/request.c
index c951d94543a9a2d2f84482d10e72e6e13f862101..39a9981b96ec5290484d3a321823b06d7bf25542 100755 (executable)
--- a/minix/servers/rs/request.c
+++ b/minix/servers/rs/request.c
@@ -867,18 +867,33 @@ message *m_ptr;
 {
   vir_bytes src_addr, dst_addr;
   int dst_proc;
-  size_t len;
+  size_t size, len;
   int s;
 
   /* Check if the call can be allowed. */
   if((s = check_call_permission(m_ptr->m_source, 0, NULL)) != OK)
       return s;
 
+  dst_proc = m_ptr->m_source;
+  dst_addr = m_ptr->m_lsys_getsysinfo.where;
+  size = m_ptr->m_lsys_getsysinfo.size;
+
   switch(m_ptr->m_lsys_getsysinfo.what) {
   case SI_PROC_TAB:
        src_addr = (vir_bytes) rproc;
        len = sizeof(struct rproc) * NR_SYS_PROCS;
        break; 
+  case SI_PROCALL_TAB:
+       /* Copy out both tables, one after the other. */
+       src_addr = (vir_bytes) rproc;
+       len = sizeof(struct rproc) * NR_SYS_PROCS;
+       if (len > size)
+               return EINVAL;
+       if ((s = sys_datacopy(SELF, src_addr, dst_proc, dst_addr, len)) != OK)
+               return s;
+       dst_addr += len;
+       size -= len;
+       /* FALLTHROUGH */
   case SI_PROCPUB_TAB:
        src_addr = (vir_bytes) rprocpub;
        len = sizeof(struct rprocpub) * NR_SYS_PROCS;
@@ -887,11 +902,9 @@ message *m_ptr;
        return(EINVAL);
   }
 
-  if (len != m_ptr->m_lsys_getsysinfo.size)
+  if (len != size)
        return(EINVAL);
 
-  dst_proc = m_ptr->m_source;
-  dst_addr = m_ptr->m_lsys_getsysinfo.where;
   return sys_datacopy(SELF, src_addr, dst_proc, dst_addr, len);
 }