[PATCH v3 6/6] staging: kpc2000: use IDA to assign card numbers.

[Jeremy Sowden <jeremy@xxxxxxxxxx>]

Previously the next card number was assigned from a static int local
variable, which was read and later incremented.  This was not thread-
safe, so now we use an IDA instead.

Updated TODO.

Signed-off-by: Jeremy Sowden <jeremy@xxxxxxxxxx>
---
 drivers/staging/kpc2000/TODO           |  1 -
 drivers/staging/kpc2000/kpc2000/core.c | 15 ++++++++++++---
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/kpc2000/TODO b/drivers/staging/kpc2000/TODO
index 669fe5bf9637..47530e23e940 100644
--- a/drivers/staging/kpc2000/TODO
+++ b/drivers/staging/kpc2000/TODO
@@ -1,6 +1,5 @@
 - the kpc_spi driver doesn't seem to let multiple transactions (to different instances of the core) happen in parallel...
 - The kpc_i2c driver is a hot mess, it should probably be cleaned up a ton.  It functions against current hardware though.
-- pcard->card_num in kp2000_pcie_probe() is a global variable and needs atomic / locking / something better.
 - would be nice if the AIO fileops in kpc_dma could be made to work
     - probably want to add a CONFIG_ option to control compilation of the AIO functions
 - if the AIO fileops in kpc_dma start working, next would be making iov_count > 1 work too
diff --git a/drivers/staging/kpc2000/kpc2000/core.c b/drivers/staging/kpc2000/kpc2000/core.c
index 80141514f7d1..3a90cdad3eb4 100644
--- a/drivers/staging/kpc2000/kpc2000/core.c
+++ b/drivers/staging/kpc2000/kpc2000/core.c
@@ -1,4 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0+
+#include <linux/idr.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/pci.h>
@@ -18,6 +19,7 @@
 #include <linux/jiffies.h>
 #include "pcie.h"
 
+static DEFINE_IDA(card_num_ida);
 
 /*******************************************************
   * SysFS Attributes
@@ -230,7 +232,6 @@ int  kp2000_pcie_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 {
     int err = 0;
     struct kp2000_device *pcard;
-    static int card_count = 1;
     int rv;
     unsigned long reg_bar_phys_addr;
     unsigned long reg_bar_phys_len;
@@ -250,8 +251,13 @@ int  kp2000_pcie_probe(struct pci_dev *pdev, const struct pci_device_id *id)
     //}
 
     //{ Step 2: Initialize trivial pcard elements
-    pcard->card_num = card_count;
-    card_count++;
+    rv = ida_simple_get(&card_num_ida, 1, INT_MAX, GFP_KERNEL);
+    if (rv < 0) {
+	err = rv;
+	dev_err(&pdev->dev, "probe: failed to get card number (%d)\n", err);
+	goto out2;
+    }
+    pcard->card_num = rv;
     scnprintf(pcard->name, 16, "kpcard%d", pcard->card_num);
 
     mutex_init(&pcard->sem);
@@ -428,6 +434,8 @@ int  kp2000_pcie_probe(struct pci_dev *pdev, const struct pci_device_id *id)
     pci_disable_device(pcard->pdev);
   out3:
     unlock_card(pcard);
+    ida_simple_remove(&card_num_ida, pcard->card_num);
+  out2:
     kfree(pcard);
     return err;
 }
@@ -461,5 +469,6 @@ void  kp2000_pcie_remove(struct pci_dev *pdev)
     pci_disable_device(pcard->pdev);
     pci_set_drvdata(pdev, NULL);
     unlock_card(pcard);
+    ida_simple_remove(&card_num_ida, pcard->card_num);
     kfree(pcard);
 }
-- 
2.20.1

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