ide-{floppy,tape}: remove packet command stack

* Add 'struct ide_atapi_pc queued_pc' to struct ide_{floppy,tape}_obj
  and switch ide*_do_request() to use it (there can be only one active
  request for a given device).

* Add 'struct ide_atapi_pc request_sense_pc' to struct ide_*_obj
  and switch ide*_retry_pc() to use it.

* Remove needless {floppy,tape}->pc assignment from ide*_setup().

* Remove no longer needed ide*_next_pc_storage(), pc_stack[],
  rq_stack_index, IDE*_PC_STACK and DBG_PC_STACK.

There should be no functional changes caused by this patch.

Cc: Borislav Petkov <petkovbb@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

1 files changed, 6 insertions, 42 deletions

diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index dd3533505e3b..ba05e03f482b 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -56,8 +56,6 @@ enum {
         DBG_CHRDEV =            (1 << 2),
         /* all remaining procedures */
         DBG_PROCS =             (1 << 3),
-        /* buffer alloc info (pc_stack) */
-        DBG_PC_STACK =  (1 << 4),
 };
 
 /* define to see debug info */
@@ -89,13 +87,6 @@ enum {
 #define IDETAPE_PC_BUFFER_SIZE          256
 
 /*
- * In various places in the driver, we need to allocate storage for packet
- * commands, which will remain valid while we leave the driver to wait for
- * an interrupt or a timeout event.
- */
-#define IDETAPE_PC_STACK                (10 + IDETAPE_MAX_PC_RETRIES)
-
-/*
  * Some drives (for example, Seagate STT3401A Travan) require a very long
  * timeout, because they don't return an interrupt or clear their busy bit
  * until after the command completes (even retension commands).
@@ -208,13 +199,6 @@ typedef struct ide_tape_obj {
         struct kref     kref;
 
         /*
-         *      Since a typical character device operation requires more
-         *      than one packet command, we provide here enough memory
-         *      for the maximum of interconnected packet commands.
-         *      The packet commands are stored in the circular array pc_stack.
-         *      pc_stack_index points to the last used entry, and warps around
-         *      to the start when we get to the last array entry.
-         *
          *      pc points to the current processed packet command.
          *
          *      failed_pc points to the last failed packet command, or contains
@@ -226,11 +210,10 @@ typedef struct ide_tape_obj {
         struct ide_atapi_pc *pc;
         /* Last failed packet command */
         struct ide_atapi_pc *failed_pc;
-        /* Packet command stack */
-        struct ide_atapi_pc pc_stack[IDETAPE_PC_STACK];
-        /* Next free packet command storage space */
-        int pc_stack_index;
+        /* used by REQ_IDETAPE_{READ,WRITE} requests */
+        struct ide_atapi_pc queued_pc;
 
+        struct ide_atapi_pc request_sense_pc;
         struct request request_sense_rq;
 
         /*
@@ -452,23 +435,6 @@ static void idetape_update_buffers(ide_drive_t *drive, struct ide_atapi_pc *pc)
 }
 
 /*
- *      idetape_next_pc_storage returns a pointer to a place in which we can
- *      safely store a packet command, even though we intend to leave the
- *      driver. A storage space for a maximum of IDETAPE_PC_STACK packet
- *      commands is allocated at initialization time.
- */
-static struct ide_atapi_pc *idetape_next_pc_storage(ide_drive_t *drive)
-{
-        idetape_tape_t *tape = drive->driver_data;
-
-        debug_log(DBG_PC_STACK, "pc_stack_index=%d\n", tape->pc_stack_index);
-
-        if (tape->pc_stack_index == IDETAPE_PC_STACK)
-                tape->pc_stack_index = 0;
-        return (&tape->pc_stack[tape->pc_stack_index++]);
-}
-
-/*
  * called on each failed packet command retry to analyze the request sense. We
  * currently do not utilize this information.
  */
@@ -693,10 +659,9 @@ static void idetape_retry_pc(ide_drive_t *drive)
 {
         struct ide_tape_obj *tape = drive->driver_data;
         struct request *rq = &tape->request_sense_rq;
-        struct ide_atapi_pc *pc;
+        struct ide_atapi_pc *pc = &tape->request_sense_pc;
 
         (void)ide_read_error(drive);
-        pc = idetape_next_pc_storage(drive);
         idetape_create_request_sense_cmd(pc);
         set_bit(IDE_AFLAG_IGNORE_DSC, &drive->atapi_flags);
         idetape_queue_pc_head(drive, pc, rq);
@@ -1006,12 +971,12 @@ static ide_startstop_t idetape_do_request(ide_drive_t *drive,
                 return ide_stopped;
         }
         if (rq->cmd[13] & REQ_IDETAPE_READ) {
-                pc = idetape_next_pc_storage(drive);
+                pc = &tape->queued_pc;
                 ide_tape_create_rw_cmd(tape, pc, rq, READ_6);
                 goto out;
         }
         if (rq->cmd[13] & REQ_IDETAPE_WRITE) {
-                pc = idetape_next_pc_storage(drive);
+                pc = &tape->queued_pc;
                 ide_tape_create_rw_cmd(tape, pc, rq, WRITE_6);
                 goto out;
         }
@@ -2412,7 +2377,6 @@ static void idetape_setup(ide_drive_t *drive, idetape_tape_t *tape, int minor)
         tape->name[1] = 't';
         tape->name[2] = '0' + minor;
         tape->chrdev_dir = IDETAPE_DIR_NONE;
-        tape->pc = tape->pc_stack;
 
         *((u16 *)&gcw) = drive->id[ATA_ID_CONFIG];