msm/qsd: smd: avoid race condition in smd channel allocation

Don't mark a channel as allocated if we failed to allocate it
(perhaps the modem updated one table but not the other, etc)

Signed-off-by: Brian Swetland <swetland@google.com>
Signed-off-by: Daniel Walker <dwalker@codeaurora.org>

1 files changed, 7 insertions, 6 deletions

diff --git a/arch/arm/mach-msm/smd.c b/arch/arm/mach-msm/smd.c
index 3fbba444e99c..34bcc327aa88 100644
--- a/arch/arm/mach-msm/smd.c
+++ b/arch/arm/mach-msm/smd.c
@@ -153,7 +153,7 @@ LIST_HEAD(smd_ch_list_dsp);
 static unsigned char smd_ch_allocated[64];
 static struct work_struct probe_work;
 
-static void smd_alloc_channel(const char *name, uint32_t cid, uint32_t type);
+static int smd_alloc_channel(const char *name, uint32_t cid, uint32_t type);
 
 static void smd_channel_probe_worker(struct work_struct *work)
 {
@@ -186,8 +186,8 @@ static void smd_channel_probe_worker(struct work_struct *work)
                 type = shared[n].ctype & SMD_TYPE_MASK;
                 if ((type == SMD_TYPE_APPS_MODEM) ||
                     (type == SMD_TYPE_APPS_DSP))
-                        smd_alloc_channel(shared[n].name, shared[n].cid, ctype);
-                smd_ch_allocated[n] = 1;
+                        if (!smd_alloc_channel(shared[n].name, shared[n].cid, ctype))
+                                smd_ch_allocated[n] = 1;
         }
 }
 
@@ -641,20 +641,20 @@ static int smd_alloc_v1(struct smd_channel *ch)
 }
 
 
-static void smd_alloc_channel(const char *name, uint32_t cid, uint32_t type)
+static int smd_alloc_channel(const char *name, uint32_t cid, uint32_t type)
 {
         struct smd_channel *ch;
 
         ch = kzalloc(sizeof(struct smd_channel), GFP_KERNEL);
         if (ch == 0) {
                 pr_err("smd_alloc_channel() out of memory\n");
-                return;
+                return -1;
         }
         ch->n = cid;
 
         if (smd_alloc_v2(ch) && smd_alloc_v1(ch)) {
                 kfree(ch);
-                return;
+                return -1;
         }
 
         ch->fifo_mask = ch->fifo_size - 1;
@@ -696,6 +696,7 @@ static void smd_alloc_channel(const char *name, uint32_t cid, uint32_t type)
         mutex_unlock(&smd_creation_mutex);
 
         platform_device_register(&ch->pdev);
+        return 0;
 }
 
 static void do_nothing_notify(void *priv, unsigned flags)