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[PATCH 3.18 17/36] MIPS: pm-cps: Drop manual cache-line alignment of ready_count

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3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Paul Burton <paul.burton@imgtec.com>

commit 161c51ccb7a6faf45ffe09aa5cf1ad85ccdad503 upstream.

We allocate memory for a ready_count variable per-CPU, which is accessed
via a cached non-coherent TLB mapping to perform synchronisation between
threads within the core using LL/SC instructions. In order to ensure
that the variable is contained within its own data cache line we
allocate 2 lines worth of memory & align the resulting pointer to a line
boundary. This is however unnecessary, since kmalloc is guaranteed to
return memory which is at least cache-line aligned (see
ARCH_DMA_MINALIGN). Stop the redundant manual alignment.

Besides cleaning up the code & avoiding needless work, this has the side
effect of avoiding an arithmetic error found by Bryan on 64 bit systems
due to the 32 bit size of the former dlinesz. This led the ready_count
variable to have its upper 32b cleared erroneously for MIPS64 kernels,
causing problems when ready_count was later used on MIPS64 via cpuidle.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Fixes: 3179d37ee1ed ("MIPS: pm-cps: add PM state entry code for CPS systems")
Reported-by: Bryan O'Donoghue <bryan.odonoghue@imgtec.com>
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@imgtec.com>
Tested-by: Bryan O'Donoghue <bryan.odonoghue@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/15383/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/mips/kernel/pm-cps.c |    9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

--- a/arch/mips/kernel/pm-cps.c
+++ b/arch/mips/kernel/pm-cps.c
@@ -55,7 +55,6 @@ DECLARE_BITMAP(state_support, CPS_PM_STA
  * state. Actually per-core rather than per-CPU.
  */
 static DEFINE_PER_CPU_ALIGNED(u32*, ready_count);
-static DEFINE_PER_CPU_ALIGNED(void*, ready_count_alloc);
 
 /* Indicates online CPUs coupled with the current CPU */
 static DEFINE_PER_CPU_ALIGNED(cpumask_t, online_coupled);
@@ -624,7 +623,6 @@ static int __init cps_gen_core_entries(u
 {
 	enum cps_pm_state state;
 	unsigned core = cpu_data[cpu].core;
-	unsigned dlinesz = cpu_data[cpu].dcache.linesz;
 	void *entry_fn, *core_rc;
 
 	for (state = CPS_PM_NC_WAIT; state < CPS_PM_STATE_COUNT; state++) {
@@ -644,16 +642,11 @@ static int __init cps_gen_core_entries(u
 	}
 
 	if (!per_cpu(ready_count, core)) {
-		core_rc = kmalloc(dlinesz * 2, GFP_KERNEL);
+		core_rc = kmalloc(sizeof(u32), GFP_KERNEL);
 		if (!core_rc) {
 			pr_err("Failed allocate core %u ready_count\n", core);
 			return -ENOMEM;
 		}
-		per_cpu(ready_count_alloc, core) = core_rc;
-
-		/* Ensure ready_count is aligned to a cacheline boundary */
-		core_rc += dlinesz - 1;
-		core_rc = (void *)((unsigned long)core_rc & ~(dlinesz - 1));
 		per_cpu(ready_count, core) = core_rc;
 	}
 

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[PATCH 3.18 00/36] 3.18.60-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 15:40 +0200
  [PATCH 3.18 15/36] arm64: cpuinfo: Missing NULL terminator in compat_hwcap_str Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 15:40 +0200
  [PATCH 3.18 34/36] cpufreq: s3c2416: double free on driver init error path Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 15:40 +0200
  [PATCH 3.18 18/36] MIPS: Fix IRQ tracing & lockdep when rescheduling Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 15:40 +0200
  [PATCH 3.18 25/36] net: korina: Fix NAPI versus resources freeing Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 15:40 +0200
  Re: [PATCH 3.18 14/36] NFSv4: fix a reference leak caused WARNING  messages Trond Myklebust <trondmy@primarydata.com> - 2017-07-03 16:40 +0200
    Re: [PATCH 3.18 14/36] NFSv4: fix a reference leak caused WARNING  messages "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org> - 2017-07-03 17:10 +0200
  [PATCH 3.18 28/36] xfrm: NULL dereference on allocation failure Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 17:20 +0200
  [PATCH 3.18 31/36] ARM: 8685/1: ensure memblock-limit is pmd-aligned Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 17:20 +0200
  [PATCH 3.18 11/36] ipv6: fix calling in6_ifa_hold incorrectly for dad work Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 17:20 +0200
  [PATCH 3.18 32/36] iommu/vt-d: Dont over-free page table directories Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 17:20 +0200
  [PATCH 3.18 06/36] decnet: dn_rtmsg: Improve input length sanitization in dnrmg_receive_user_skb Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 17:20 +0200
  [PATCH 3.18 27/36] xfrm: fix stack access out of bounds with CONFIG_XFRM_SUB_POLICY Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 17:20 +0200
  [PATCH 3.18 05/36] net: dont call strlen on non-terminated string in dev_set_alias() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 17:20 +0200
  [PATCH 3.18 29/36] xfrm: Oops on error in pfkey_msg2xfrm_state() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 17:20 +0200
  [PATCH 3.18 07/36] Fix an intermittent pr_emerg warning about lo becoming free. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 17:20 +0200
  [PATCH 3.18 20/36] drm/vmwgfx: Free hash table allocated by cmdbuf managed res mgr Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 17:20 +0200
  [PATCH 3.18 16/36] MIPS: Avoid accidental raw backtrace Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 17:20 +0200
  [PATCH 3.18 14/36] NFSv4: fix a reference leak caused WARNING messages Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 17:20 +0200
  [PATCH 3.18 08/36] net: caif: Fix a sleep-in-atomic bug in cfpkt_create_pfx Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 17:20 +0200
  [PATCH 3.18 30/36] watchdog: bcm281xx: Fix use of uninitialized spinlock. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 17:20 +0200
  [PATCH 3.18 17/36] MIPS: pm-cps: Drop manual cache-line alignment of ready_count Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 17:20 +0200
  Re: [PATCH 3.18 00/36] 3.18.60-stable review Guenter Roeck <linux@roeck-us.net> - 2017-07-03 21:40 +0200

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