1. Motivate in some way the changes that need to be made.

2. Show the semantic patch in rule9_1.cocci.  This could also be developed
   incrementally, with first the lines for get and put, then the line for
   the error checking on hostptr, then the - and + line for moving the
   declaration of hostptr to the parameter list.  Finally, drop the hostno
   parameter.  Explain the metavariables.  Note that a rule is
   automatically generated to update the prototype of the proc_info
   function, if one is available.

3. Apply it to scsiglue.c and show what has changed.

4. Some issues:

   * In nsp_cs.c (and a lot of other files), there is no call to the put
     function.  Indeed, the reason for the CE was that driver programmers
     were forgetting to call the put function.  We thus would like to make
     it optional, the idea being that if we find it we should delete it,
     but if we don't find it, the rest of the transformation should still
     take place.

   * In g_NCR5380.c, there is no error checking on the result of calling
     the get function.  Thus, that has to be optional as well.  The result
     of making both of these changes is in rule9_2.cocci.

   * In sym53c8xx.c, there are no braces around the if branch in the error
     handling code.  Explain about the isomorphisms.

   * In nsp_cs.c, hostptr is compared to NULL.  There is an isomorphism for
     that as well.

   * The function is essentially identified by the types of its
     parameters.  Since there are quite a lot of them, with quite varied
     typed, this is probably enough to uniquely identify the function
     within each driver in practice.  But for greater safety, we should
     describe the function in terms of how it interacts with the SCSI
     library, because it is the SCSI library that will be responsible for
     supplying the extra argument.  For this we add a new rule
     (rule9_3.cocci).  This rule identifies the function as the one that is
     stored in the proc_info field of a structure of type SHT (also given
     the typedef name of Scsi_Host_Template).  Isomorphisms take case of
     the case where this assignment has other forms, eg involving a pointer
     to the structure or is part of a top-level structure initialization.

     Now we want to inherit the binding of proc_info_func from the first
     rule to the second one.  For this, we give the first one a name, and
     use that name in declaring the proc_info_func metavariable in the
     second rule.  The second rule will be applied once for each successful
     match of the first rule, but in practice, there is only one.

5. The transformation that is implemented is not yet complete, as one can
   see by comparing with the .res file.  We also have to rename the hostno
   variable everywhere that it occurs.  Because it can in principle occur
   anywhere, we make a separate rule to avoid cluttering up the previous
   one.  This rule inherits the name of the proc_info function from rule1
   and the names of the hostno and hostptr variables from rule2.  The
   transformation is to replace occurrences of hostno by a reference to the
   host_no field of hostptr everywhere hostno occurs, as indicated by the
   <... ...>.

6. Finally, the proc_info function may be called from other places within
   the current driver.  These cases must be updated as well with the new
   argument.  For this, we have to find an appropriate value somewhere.
   Because the get function has been deprecated, the driver will normally
   get this information as a parameter, and that is the only case we
   consider here.  The name of the function enclosing the call is arbitrary
   (as indicated by a metavariable) as is the position of the
   Scsi_Host-typed parameter (as indicated by the dots in the parameter
   list).  As for the previous rule, we use <... ...> to update a call to
   the proc_info function wherever it occurs.  Note that although we have
   used the same names as for the parameter list in rule2, buffer, start,
   etc. are now arbitrary expressions.